def get_membership_session(self, proxy=None):
if proxy is None:<EOL><INDENT>raise NullArgument()<EOL><DEDENT>raise Unimplemented()<EOL>
Gets the session for querying memberships.

        arg:    proxy (osid.proxy.Proxy): a proxy
        return: (osid.resource.MembershipSession) - a
                ``MembershipSession``
        raise:  NullArgument - ``proxy`` is ``null``
        raise:  OperationFailed - unable to complete request
        raise:  Unimplemented - ``supports_membership()`` is ``false``
        *compliance: optional -- This method must be implemented if
        ``support_membership()`` is ``true``.*