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  • Irregular layout ItemsControl

    - by firoso
    I have a strange layout for an ItemsControl. I have a 4x6 grid with the following pattern: 1 2 3 4 13 14 15 16 5 6 7 8 17 18 19 20 9 10 11 12 21 22 23 24 Is there an easy way to do this? should I be using 6 Items Controls and take "sections" of my list? is there a good way to do this? What about notification? It's important to note that I may, or may not, have all 24 entries present, but the layout needs to be maintained (think of it like filled slots on a bingo card or something)

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  • Is it inefficient to access a python class member container in a loop statement?

    - by Dave
    Hi there. I'm trying to adopt some best practices to keep my python code efficient. I've heard that accessing a member variable inside of a loop can incur a dictionary lookup for every iteration of the loop, so I cache these in local variables to use inside the loop. My question is about the loop statement itself... if I have the following class: class A(object): def init(self) self.myList = [ 'a','b','c', 'd', 'e' ] Does the following code in a member function incur one, or one-per-loop-iteration (5) dictionary lookups? for letter in self.myList: print letter IE, should I adopt the following pattern, if I am concerned about efficiency... localList = self.myList for letter in localList: print letter or is that actually LESS efficient due to the local variable assign? Note, I am aware that early optimization is a dangerous pitfall if I'm concerned about the overall efficiency of code development. Here I am specifically asking about the efficiency of the code, not the coding. Thanks in advance! D

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  • django-haystack urlpatterns include('haystack.urls') where does it lead to?

    - by Eugene
    I've recently begun to learn/install django/haystack/solr. Following the tutorial given in haystack site, I have urlpatterns = pattern('', r'^search/', include('haystack.urls')) I found haystack installed in /usr/local/lib/python2.6/dist-packages/haystack and located urls.py there. It has urlpatterns=patterns('haystack.views', url(r'^$', SearchView(), name='haystack_search'),) I thought the second argument of url() should be callable object. I looked at the views.py and SearchView is a class. What is going on here? What's get called eventually?

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  • Dynamically adding Views in Silverlight & MVVM

    - by dvox
    Hi all, I am starting to re-write my whole silverlight business application in the MVVM pattern; My first stop-point is this: I have a page (View1) with corresponding ViewModel1 (with a property 'IEnumerable AllData'); Now, within this View, I want to have i.e. a tree-view control, in which one node will be populated with another View2; My question is: 1. How to do it? - I can't loop through the AllData property since it is asynchronously loaded... - thus I don't know the number of View2s' to insert - I don't know how to do it from ViewModel1 :( Will I need ViewModel2 with property 'MyDataEntity CurrentData'? or I can bind to AllData property from ViewModel1 Can you help me out? Thanks

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  • iPhone UIImage number recognition

    - by Skeep
    Hi All, I have a small UIImage (jpg) with a single typed number. I want to be able to read the number with some kind of pattern recognition. I'm really not sure where to start, so any help would be appreciated. my initial idea was to compare this image with other images. For instance compare the image with that of a 1,2,3, etc until a match was found. That just seems slow and cumbersome and wondered if there was a better way to do it? Thanks

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  • Force an object to be allocated on the heap

    - by Warren Seine
    A C++ class I'm writing uses shared_from_this() to return a valid boost::shared_ptr<>. Besides, I don't want to manage memory for this kind of object. At the moment, I'm not restricting the way the user allocates the object, which causes an error if shared_from_this() is called on a stack-allocated object. I'd like to force the object to be allocated with new and managed by a smart pointer, no matter how the user declares it. I thought it could be done through a proxy or an overloaded new operator, but I can't find a proper way of doing that. Is there a common design pattern for such usage? If it's not possible, how can I test it at compile time?

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  • What books help one to learn to read code?

    - by Daniel
    Lion's Commentary on Unix Sixth Edition with Source Code is a wonderful book to learn how to read code. Reading code is important -- how does one learn how to write excellent code without having read excellent code? But, sadly, while great writers, of fiction and non-fiction, all spend a great deal of time reading stuff, we, programmers, seem to avoid it like the plague. Worse still, programming books usually go the same way. They might show a pattern or a style, but they often avoid showing good, complex code, and helping one go through it. There are exceptions, of course. I hope. So, with that in mind, what books are to be found which help one learn how to read code?

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  • A faster alternative to Pandas `isin` function

    - by user3576212
    I have a very large data frame df that looks like: ID Value1 Value2 1345 3.2 332 1355 2.2 32 2346 1.0 11 3456 8.9 322 And I have a list that contains a subset of IDs ID_list. I need to have a subset of df for the ID contained in ID_list. Currently, I am using df_sub=df[df.ID.isin(ID_list)] to do it. But it takes a lot time. IDs contained in ID_list doesn't have any pattern, so it's not within certain range. (And I need to apply the same operation to many similar dataframes. I was wondering if there is any faster way to do this. Will it help a lot if make ID as the index? Thanks!

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  • Should I always release self for failed init methods?

    - by leo
    Should I always release self when there is a failure inside init, or should I only do so if I have initialized instance variables first? To put it another way, is this pattern valid? Is there a time when I shouldn't release self inside an init method, or should I assume that if the control flow enters init, self has at least a retain count of 1? - (id)init { if ((self = [super init]) == nil) { [self release]; return nil; } //do some init stuff if (somethingFailed) { [self release]; return nil; } return self; }

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  • What difference does it make to use several script blocks on a web page?

    - by Jan Aagaard
    What difference does it make to use more than one script block on a web page? I have pasted in the standard code for including Google Analytics as an example, and I have seen the same pattern used in other places. Why is this code separated into two separate script blocks instead of just using a single one? <script type="text/javascript"> var gaJsHost = (("https:" == document.location.protocol) ? "https://ssl." : "http://www."); document.write(unescape("%3Cscript src='" + gaJsHost + "google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E")); </script> <script type="text/javascript"> try{ var pageTracker = _gat._getTracker("UA-xxxxxx-x"); pageTracker._trackPageview(); } catch(err) {} </script>

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  • Google Gears hangs when capturing (unmanaged resource store)

    - by Gus
    Our code was written based on the example from Google Gears' own docs. We're using an unmanaged resource store. So we declare the files in an array, create the store, and capture all the files. Trouble is, the capturing process hangs. It always hangs on a random file (no discernible pattern has emerged), and when you reload the page, it always successfully captures. We're capturing 48 files. It seems to have nothing to do with the files themselves, as it hangs on every file type. I've seen it hang on the 6th file or the 47th. Windows and Mac. FF, IE, and Safari. We are not using a WorkerPool, and I'm thinking this may be necessary. Any other ideas why it would hang?

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  • interview questions for a test lead

    - by PJ
    Maybe this question has been asked although I didn't find the answer. I am going to attend an interview for a test lead. can you tell me the pattern of questions I will have to face other than the normal question that I was facing previously like What is Software testing? What is Bug life cycle? or Grilling me on my project experience. Also I wnat to know when they are going to hire me for a test lead what would they want to see as an extra add ons?

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  • What elegant method callback design should be used ?

    - by ereOn
    Hi, I'm surprised this question wasn't asked before on SO (well, at least I couldn't find it). Have you ever designed a method-callback pattern (something like a "pointer" to a class method) in C++ and, if so, how did you do it ? I know a method is just a regular function with some hidden this parameter to serve as a context and I have a pretty simple design in mind. However, since things are often more complex than they seem to, I wonder how our C++ gurus would implement this, preferably in an elegant and standard way. All suggestions are welcome !

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  • MVC - Sanitizing data, where?

    - by dierre
    I'm using CakePHP but it's a question about the MVC pattern. I have in my form the input-text for the tags (separated by commas). To add the tags I've created a Tag model method that basically check if the tag exists and then add the new tag or just a new unit in the tag counter (the Tag model has these fields: id, name, slug, count). In the controller I explode the tags field and pass one tag at a time. The question is: where do I sanitize data? In the controller or in the model method? I think it should be in the controller because that's where I explode but in term of reusability I think I should sanitize data in the model. What do you think?

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  • Using Remote Web Page to Initialize iPhone App

    - by Chris_K
    My iPhone app relies on a vendor's XML feed to provide data. But that feed is not locked down. The vendor could change the format of the XML at any time, although so far they've promised not to. Since I might want to tell my app to use a different URL for its data source, I'd like to set up a single "Command Central" Web page, on my own server, to direct the app to the correct data source. In other words, each time my app starts, in the background and unseen by the user, it would visit "http://www.myserver.com/iphoneapp_data_sources.xml" to retrieve the URL for retrieving data from my vendor. That way, if my vendor suddenly changes the exact URL or the XML feed that the app needs, I can update that Web page and ensure that all installations of the app are using the correct XML feed. Does anyone have any advice or examples showing this kind of approach? It seems as if this must be a common problem, but so far I haven't found a well-established design pattern that fits it.

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  • Scala match/compare enumerations

    - by williamstw
    I have an enumeration that I want to use in pattern matches in an actor. I'm not getting what i'd expect and, now, I'm suspecting I'm missing something simple. My enumeration, object Ops extends Enumeration { val Create = Value("create") val Delete = Value("delete") } Then, I create an Ops from a String: val op = Ops.valueOf("create") Inside my match, I have: case (Ops.Create, ...) But Ops.Create doesn't seem to equal ops.valueOf("create") The former is just an atom 'create' and the later is Some(create) Hopefully, this is enough info for someone to tell me what I'm missing... Thanks

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  • Help me understand the code snippet in c#

    - by Benny
    I am reading this blog: Pipes and filters pattern I am confused by this code snippet: public class Pipeline<T> { private readonly List<IOperation<T>> operations = new List<IOperation<T>>(); public Pipeline<T> Register(IOperation<T> operation) { operations.Add(operation); return this; } public void Execute() { IEnumerable<T> current = new List<T>(); foreach (IOperation<T> operation in operations) { current = operation.Execute(current); } IEnumerator<T> enumerator = current.GetEnumerator(); while (enumerator.MoveNext()); } } what is the purpose of this statement: while (enumerator.MoveNext());? seems this code is a noop.

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  • php regex to split invoice line item description

    - by user1053700
    I am attempting to split strings like the following: An item (Item A) which may contain 89798 numbers and letters @ $550.00 4 of Item B @ $420.00 476584 of Item C, with a larger quantity and different currency symbol @ £420.00 into: array( 0 => 1 1 => "some item which may contain 89798 numbers and letters" 2 => $550.00 ); does that make sense? I am looking for a regex pattern which will split the quantity, description, and price (including symbol). the strings will always be: qty x description @ price+symbol so i assume the regex would be something like: `(match a number and only a number) x (get description letters and numbers before the @ symbol) @ (match the currency symbol and price)` How should I approach this?

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  • WCF Service returning 400 error: The body of the message cannot be read because it is empty

    - by Josh
    I have a WCF service that is causing a bit of a headache. I have tracing enabled, I have an object with a data contract being built and passed in, but I am seeing this error in the log: <TraceData> <DataItem> <TraceRecord xmlns="http://schemas.microsoft.com/2004/10/E2ETraceEvent/TraceRecord" Severity="Error"> <TraceIdentifier>http://msdn.microsoft.com/en-US/library/System.ServiceModel.Diagnostics.ThrowingException.aspx</TraceIdentifier> <Description>Throwing an exception.</Description> <AppDomain>efb0d0d7-1-129315381593520544</AppDomain> <Exception> <ExceptionType>System.ServiceModel.ProtocolException, System.ServiceModel, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</ExceptionType> <Message>There is a problem with the XML that was received from the network. See inner exception for more details.</Message> <StackTrace> at System.ServiceModel.Channels.HttpRequestContext.CreateMessage() at System.ServiceModel.Channels.HttpChannelListener.HttpContextReceived(HttpRequestContext context, Action callback) at System.ServiceModel.Activation.HostedHttpTransportManager.HttpContextReceived(HostedHttpRequestAsyncResult result) at System.ServiceModel.Activation.HostedHttpRequestAsyncResult.HandleRequest() at System.ServiceModel.Activation.HostedHttpRequestAsyncResult.BeginRequest() at System.ServiceModel.Activation.HostedHttpRequestAsyncResult.OnBeginRequest(Object state) at System.Runtime.IOThreadScheduler.ScheduledOverlapped.IOCallback(UInt32 errorCode, UInt32 numBytes, NativeOverlapped* nativeOverlapped) at System.Runtime.Fx.IOCompletionThunk.UnhandledExceptionFrame(UInt32 error, UInt32 bytesRead, NativeOverlapped* nativeOverlapped) at System.Threading._IOCompletionCallback.PerformIOCompletionCallback(UInt32 errorCode, UInt32 numBytes, NativeOverlapped* pOVERLAP) </StackTrace> <ExceptionString> System.ServiceModel.ProtocolException: There is a problem with the XML that was received from the network. See inner exception for more details. ---&amp;gt; System.Xml.XmlException: The body of the message cannot be read because it is empty. --- End of inner exception stack trace --- </ExceptionString> <InnerException> <ExceptionType>System.Xml.XmlException, System.Xml, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</ExceptionType> <Message>The body of the message cannot be read because it is empty.</Message> <StackTrace> at System.ServiceModel.Channels.HttpRequestContext.CreateMessage() at System.ServiceModel.Channels.HttpChannelListener.HttpContextReceived(HttpRequestContext context, Action callback) at System.ServiceModel.Activation.HostedHttpTransportManager.HttpContextReceived(HostedHttpRequestAsyncResult result) at System.ServiceModel.Activation.HostedHttpRequestAsyncResult.HandleRequest() at System.ServiceModel.Activation.HostedHttpRequestAsyncResult.BeginRequest() at System.ServiceModel.Activation.HostedHttpRequestAsyncResult.OnBeginRequest(Object state) at System.Runtime.IOThreadScheduler.ScheduledOverlapped.IOCallback(UInt32 errorCode, UInt32 numBytes, NativeOverlapped* nativeOverlapped) at System.Runtime.Fx.IOCompletionThunk.UnhandledExceptionFrame(UInt32 error, UInt32 bytesRead, NativeOverlapped* nativeOverlapped) at System.Threading._IOCompletionCallback.PerformIOCompletionCallback(UInt32 errorCode, UInt32 numBytes, NativeOverlapped* pOVERLAP) </StackTrace> <ExceptionString>System.Xml.XmlException: The body of the message cannot be read because it is empty.</ExceptionString> </InnerException> </Exception> </TraceRecord> </DataItem> </TraceData> So, here is my service interface: [ServiceContract] public interface IRDCService { [OperationContract] Response<Customer> GetCustomer(CustomerRequest request); [OperationContract] Response<Customer> GetSiteCustomers(CustomerRequest request); } And here is my service instance public class RDCService : IRDCService { ICustomerService customerService; public RDCService() { //We have to locate the instance from structuremap manually because web services *REQUIRE* a default constructor customerService = ServiceLocator.Locate<ICustomerService>(); } public Response<Customer> GetCustomer(CustomerRequest request) { return customerService.GetCustomer(request); } public Response<Customer> GetSiteCustomers(CustomerRequest request) { return customerService.GetSiteCustomers(request); } } The configuration for the web service (server side) looks like this: <system.serviceModel> <diagnostics> <messageLogging logMalformedMessages="true" logMessagesAtServiceLevel="true" logMessagesAtTransportLevel="true" /> </diagnostics> <services> <service behaviorConfiguration="MySite.Web.Services.RDCServiceBehavior" name="MySite.Web.Services.RDCService"> <endpoint address="http://localhost:27433" binding="wsHttpBinding" contract="MySite.Common.Services.Web.IRDCService"> <identity> <dns value="localhost:27433" /> </identity> </endpoint> <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" /> </service> </services> <behaviors> <serviceBehaviors> <behavior name="MySite.Web.Services.RDCServiceBehavior"> <!-- To avoid disclosing metadata information, set the value below to false and remove the metadata endpoint above before deployment --> <serviceMetadata httpGetEnabled="true"/> <!-- To receive exception details in faults for debugging purposes, set the value below to true. Set to false before deployment to avoid disclosing exception information --> <serviceDebug includeExceptionDetailInFaults="true"/> <dataContractSerializer maxItemsInObjectGraph="6553600" /> </behavior> </serviceBehaviors> </behaviors> </system.serviceModel> Here is what my request object looks like [DataContract] public class CustomerRequest : RequestBase { [DataMember] public int Id { get; set; } [DataMember] public int SiteId { get; set; } } And the RequestBase: [DataContract] public abstract class RequestBase : IRequest { #region IRequest Members [DataMember] public int PageSize { get; set; } [DataMember] public int PageIndex { get; set; } #endregion } And my IRequest interface public interface IRequest { int PageSize { get; set; } int PageIndex { get; set; } } And I have a wrapper class around my service calls. Here is the class. public class MyService : IMyService { IRDCService service; public MyService() { //service = new MySite.RDCService.RDCServiceClient(); EndpointAddress address = new EndpointAddress(APISettings.Default.ServiceUrl); BasicHttpBinding binding = new BasicHttpBinding(BasicHttpSecurityMode.None); binding.TransferMode = TransferMode.Streamed; binding.MaxBufferSize = 65536; binding.MaxReceivedMessageSize = 4194304; ChannelFactory<IRDCService> factory = new ChannelFactory<IRDCService>(binding, address); service = factory.CreateChannel(); } public Response<Customer> GetCustomer(CustomerRequest request) { return service.GetCustomer(request); } public Response<Customer> GetSiteCustomers(CustomerRequest request) { return service.GetSiteCustomers(request); } } and finally, the response object. [DataContract] public class Response<T> { [DataMember] public IEnumerable<T> Results { get; set; } [DataMember] public int TotalResults { get; set; } [DataMember] public int PageIndex { get; set; } [DataMember] public int PageSize { get; set; } [DataMember] public RulesException Exception { get; set; } } So, when I build my CustomerRequest object and pass it in, for some reason it's hitting the server as an empty request. Any ideas why? I've tried upping the object graph and the message size. When I debug it stops in the wrapper class with the 400 error. I'm not sure if there is a serialization error, but considering the object contract is 4 integer properties I can't imagine it causing an issue.

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  • How to handle recursive parent/child problems like this?

    - by lsdude
    In web dev I come across these problems a lot. For example, we have a giant list of URLs that are in this format: /businesses /businesses/food /businesses/food/wendys /businesses/food/wendys/chili /businesses/food/wendys/fries /businesses/food/wendys/chicken-nuggets /businesses/pharmacy/cvs /businesses/pharmacy/cvs/toothpaste /businesses/pharmacy/cvs/toothpaste/brand ... and then we need to output each one, where the parent category is in h1 tags, the child is in h2 tags, and the children of that are in h3 tags. I can handle this but I feel my code is messy. I'm sure there is a design pattern I can use? Langs are ruby/php usually. how would you handle this?

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  • Insert A Line At The Beginnig Of A File

    - by thebourneid
    I'm trying to insert/add a line 'COMMENT DUMMY' at the beginnig of a file as a first row if /PATTERN/ not found. I know how to do this with OPEN CLOSE function. Probably after reading the file it should look something like this: open F, ">", $fn or die "could not open file: $!"; ; print F "COMMENT DUMMY\n", @array; close F; But I have a need to implement this with the use of the Tie::File function and don't know how. use strict; use warnings; use Tie::File; my $fn = 'test.txt'; tie my @lines, 'Tie::File', $fn or die "could not tie file: $!"; untie @lines;

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  • What's the fastest way to compare two objects in PHP?

    - by johnnietheblack
    Let's say I have an object - a User object in this case - and I'd like to be able to track changes to with a separate class. The User object should not have to change it's behavior in any way for this to happen. Therefore, my separate class creates a "clean" copy of it, stores it somewhere locally, and then later can compare the User object to the original version to see if anything changed during its lifespan. Is there a function, a pattern, or anything that can quickly compare the two versions of the User object? Option 1 Maybe I could serialize each version, and directly compare, or hash them and compare? Option 2 Maybe I should simply create a ReflectionClass, run through each of the properties of the class and see if the two versions have the same property values? Option 3 Maybe there is a simple native function like objects_are_equal($object1,$object2);? What's the fastest way to do this?

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  • Optimizing NSNumber numberWithInt:

    - by Riviera
    I am profiling an iPhone app and I noticed a strange pattern. In a certain block of code that's called quite frequently... [item setQuadrant:[NSNumber numberWithInt:a]]; [item setIndex:[NSNumber numberWithInt:b]]; [item setTimestamp:[NSNumber numberWithInt:c]]; [item setState:[NSNumber numberWithInt:d]]; [item setCompletionPercentage:[NSNumber numberWithInt:e]]; [item setId_:[NSNumber numberWithInt:f]]; ...the first call to [NSNumber numberWithInt:] takes an inordinate amount of time, in the order of 10-15x that of the remaining calls. I've verified that the results are consistent if I shuffle the lines (the first line is always the slow one, by the same ratio). Is there something going on that I'm not aware of? Perhaps this happens because this block is inside a try/catch?

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  • What is the purpose of this delegate usage?

    - by Kev
    Whilst poking around some code in .NET Reflector in an app I don't have the source code for I found this: if (DeleteDisks) { using (List<XenRef<VDI>>.Enumerator enumerator3 = list.GetEnumerator()) { MethodInvoker invoker2 = null; XenRef<VDI> vdiRef; while (enumerator3.MoveNext()) { vdiRef = enumerator3.Current; if (invoker2 == null) { // // Why do this? // invoker2 = delegate { VDI.destroy(session, vdiRef.opaque_ref); }; } bestEffort(ref caught, invoker2); } } } if (caught != null) { throw caught; } private static void bestEffort(ref Exception caught, MethodInvoker func) { try { func(); } catch (Exception exception) { log.Error(exception, exception); if (caught == null) { caught = exception; } } } Why not call VDI.destroy() directly. Is this just a way of wrapping the same pattern of try { do something } catch { log error } if it's used a lot?

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  • Div horizontal aligning, one fixed, one adaptive

    - by Dorian McHensie
    Hello everyone. I would like to create a vertical splitted site structure using two divs: My intention is to have d2 next to d1 in a horizontal align structure (same line). What i get is not this. In fact using that code, d2 does not take the remaining space, but collapses to the min width. if I use WRONG because d2 goes down and takes all the space (but both divs are in different lines). HOW TO REACH MY OBJECTIVE? Is there a design pattern for this problem???? Thanks.

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