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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_authorization_vault_assignment_session(self):
 """Gets the session for assigning authorizations to vault mappings. return: (osid.authorization.AuthorizationVaultAssignmentSession) - a ``AuthorizationVaultAssignmentSession`` raise: OperationFailed - unable to complete request raise: Unimplemented - ``supports_authorization_vault_assignment()`` is ``false`` *compliance: optional -- This method must be implemented if ``supports_authorization_vault_assignment()`` is ``true``.* """

        if not self.supports_authorization_vault_assignment():
            raise errors.Unimplemented()
        # pylint: disable=no-member
        return sessions.AuthorizationVaultAssignmentSession(runtime=self._runtime)