def get_objectives_by_parent_genus_type(self, objective_genus_type=None):
raise Unimplemented()<EOL>
Gets an ObjectiveList corresponding to the given objective genus
        Type and include any additional objective with genus types
        derived from the specified Type.
        In plenary mode, the returned list contains all known objectives
        or an error results. Otherwise, the returned list may contain
        only those objectives that are accessible through this session
        arg:    objectiveGenusType (osid.type.Type): an objective genus
                type
        return: (osid.learning.ObjectiveList) - the returned Objective
                list
        raise:  NullArgument - objectiveGenusType is null
        raise:  OperationFailed - unable to complete request
        raise:  PermissionDenied - authorization failure
        compliance: mandatory - This method must be implemented.