def get_proficiency_objective_bank_assignment_session(self):
raise Unimplemented()<EOL>
Gets the ``OsidSession`` associated with assigning proficiencys to objective banks.

        return:
                (osid.learning.ProficiencyObjectiveBankAssignmentSession
                ) - a ``ProficiencyObjectiveBankAssignmentSession``
        raise:  OperationFailed - unable to complete request
        raise:  Unimplemented -
                ``supports_proficiency_objective_bank_assignment()`` is
                ``false``
        *compliance: optional -- This method must be implemented if
        ``supports_proficiency_objective_bank_assignment()`` is
        ``true``.*