Even after studying the examples, I'm having trouble figuring out how to extract ranges using a composite key on a MultiIndex container.

typedef multi_index_container<
  boost::shared_ptr< Host >,
  indexed_by< 
    hashed_unique< const_mem_fun<Host,int,&Host::getID> >, // ID index
    ordered_non_unique< const_mem_fun<Host,int,&Host::getAgeInY> >, // Age index
    ordered_non_unique< const_mem_fun<Host,int,&Host::getHousehold> >, // Household index
    ordered_non_unique< // Age & eligibility status index
      composite_key<
         Host,
        const_mem_fun<Host,int,&Host::getAgeInY>,
        const_mem_fun<Host,bool,&Host::isPaired>
        >
       >
    > // end indexed_by
  > HostContainer;

My goal is to get an iterator pointing to the first of the subset of elements in HostContainer hmap that has age partnerAge and returns false to Host::isPaired():

  std::pair< hmap::iterator,hmap::iterator > pit = hmap.equal_range(boost::make_tuple( partnerAge, false ) );

I think this is very wrong.

1. How/Where do I specify the iterator index (which should be 3 for age & eligibility)? I will include other composite keys in the future.
2. What exactly are the two iterators in std::pair? (I'm copying syntax from an example that I don't understand.)
3. I would ideally use std::count to calculate the number of elements of age partnerAge that are eligible (return false to Host::isPaired()). What is the syntax for extracting the sorted index that meets these requirements?

I'm obviously still learning C++ syntax. Thanks in advance for any help.