For instance, say I wanted a function to escape a string for use in HTML (as in Django's escape filter):

    def escape(string):
    """
    Returns the given string with ampersands, quotes and angle brackets encoded.
    """        return string.replace('&', '&amp;').replace('<', '&lt;').replace('>', '&gt;').replace("'", '&#39;').replace('"', '&quot;')

This works, but it gets ugly quickly and appears to have poor algorithmic performance (in this example, the string is repeatedly traversed 5 times). What would be better is something like this:

    def escape(string):
    """
    Returns the given string with ampersands, quotes and angle brackets encoded.
    """
    # Note that ampersands must be escaped first; the rest can be escaped in 
    # any order.
    return replace_multi(string.replace('&', '&'),
                         {'<': '&lt;', '>': '&gt;', "'": '&#39;', '"': '&quot;'})

Does such a function exist, or is the standard Python idiom to use what I wrote before?