'Get the prefix and id from the namespace name.
:param ns_name: The name of the namespace
:returns: tuple with prefix and id or None if no prefix matches'

def get_prefix_and_id(self, ns_name):

    prefix = namespaces.get_prefix_from_ns_name(ns_name)
    if (prefix in self.ns_prefix_to_class_map):
        identifier = namespaces.get_id_from_ns_name(ns_name)
        return (prefix, identifier)
