Custom Django-Piston authentication backend that can handle multiple types of auth methods

MultiAuthentication.py

# Class that can help django-piston process multiple types of authentication
# Example usage:
#
# from piston.authentication import HttpBasicAuthentication
# from somewhere import OtherCustomAuthModule
#
# httpAuth = HttpBasicAuthentication(realm="CycleCloud")
# otherAuth = OtherCustomAuthModule()
#
# auth = MultiAuthentication([httpAuth, otherAuth]) 
# Use auth as you would any other authentication object in django-piston

class MultiAuthentication(object):
    """ Authenticated Django-Piston against multiple types of authentication """
    
    def __init__(self, auth_types):
        """ Takes a list of authenication objects to try against, the default
        authentication type to try is the first in the list. """
        self.auth_types = auth_types
        self.selected_auth = auth_types[0]
        
    def is_authenticated(self, request):
        """ Try each authentication type in order and use the first that succeeds """
        authenticated = False
        for auth in self.auth_types:
            authenticated = auth.is_authenticated(request)
            if authenticated:
                selected_auth = auth
                break
        return authenticated
    
    def challenge(self):
        """ Return the challenge for whatever the selected auth type is (or the default 
        auth type which is the first in the list)"""
        return self.selected_auth.challenge()