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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _default_key_normalizer(key_class, request_context):
 """ Create a pool key out of a request context dictionary. According to RFC 3986, both the scheme and host are case-insensitive. Therefore, this function normalizes both before constructing the pool key for an HTTPS request. If you wish to change this behaviour, provide alternate callables to ``key_fn_by_scheme``. :param key_class: The class to use when constructing the key. This should be a namedtuple with the ``scheme`` and ``host`` keys at a minimum. :type key_class: namedtuple :param request_context: A dictionary-like object that contain the context for a request. :type request_context: dict :return: A namedtuple that can be used as a connection pool key. :rtype: PoolKey """

    # Since we mutate the dictionary, make a copy first
    context = request_context.copy()
    context['scheme'] = context['scheme'].lower()
    context['host'] = context['host'].lower()

    # These are both dictionaries and need to be transformed into frozensets
    for key in ('headers', '_proxy_headers', '_socks_options'):
        if key in context and context[key] is not None:
            context[key] = frozenset(context[key].items())

    # The socket_options key may be a list and needs to be transformed into a
    # tuple.
    socket_opts = context.get('socket_options')
    if socket_opts is not None:
        context['socket_options'] = tuple(socket_opts)

    # Map the kwargs to the names in the namedtuple - this is necessary since
    # namedtuples can't have fields starting with '_'.
    for key in list(context.keys()):
        context['key_' + key] = context.pop(key)

    # Default to ``None`` for keys missing from the context
    for field in key_class._fields:
        if field not in context:
            context[field] = None

    return key_class(**context)