def get_repositories_by_query(self, repository_query=None):
return<EOL>
Gets a list of ``Repositories`` matching the given repository query.

        :param repository_query: the repository query
        :type repository_query: ``osid.repository.RepositoryQuery``
        :return: the returned ``RepositoryList``
        :rtype: ``osid.repository.RepositoryList``
        :raise: ``NullArgument`` -- ``repository_query`` is ``null``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``PermissionDenied`` -- authorization failure
        :raise: ``Unsupported`` -- ``repository_query`` is not of this service

        *compliance: mandatory -- This method must be implemented.*