def get_key_resource(self):
return Agent(self.get_key_resource_id())<EOL>
Gets the key resource of this entry.

        The key resource may be a student or other applicable key to
        identify a row of grading entries.

        return: (osid.resource.Resource) - the key resource
        raise:  OperationFailed - unable to complete request
        *compliance: mandatory -- This method must be implemented.*