code: def get_session_class(cls, interface_type, resource_class):
          
          try:
              return cls._session_classes[(interface_type, resource_class)]
          except KeyError:
              raise ValueError('No class registered for %s, %s' % (interface_type, resource_class))
docs: Return the session class for a given interface type and resource class.
  
          :type interface_type: constants.InterfaceType
          :type resource_class: str
          :return: Session