@abc.abstractmethod<EOL><INDENT>def get_installation(self, installation_id):<DEDENT>
return<EOL>
Gets the ``Installation`` specified by its ``Id``.

        In plenary mode, the exact ``Id`` is found or a ``NotFound``
        results. Otherwise, the returned ``Installation`` may have a
        different ``Id`` than requested, such as the case where a
        duplicate ``Id`` was assigned to an ``Installation`` and
        retained for compatibility.

        :param installation_id: ``Id`` of the ``Installation``
        :type installation_id: ``osid.id.Id``
        :return: the installation
        :rtype: ``osid.installation.Installation``
        :raise: ``NotFound`` -- ``installation_id`` not found
        :raise: ``NullArgument`` -- ``installation_id`` is ``null``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``PermissionDenied`` -- authorization failure

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