@abc.abstractmethod<EOL><INDENT>def get_installations_by_query(self, installation_query):<DEDENT>
return<EOL>
Gets a list of ``Installations`` matching the given installation query.

        :param installation_query: the installation query
        :type installation_query: ``osid.installation.InstallationQuery``
        :return: the returned ``InstallationList``
        :rtype: ``osid.installation.InstallationList``
        :raise: ``NullArgument`` -- ``installation_query`` is ``null``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``PermissionDenied`` -- authorization failure
        :raise: ``Unsupported`` -- ``installation_query`` is not of this service

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