@abc.abstractmethod<EOL><INDENT>def get_installations_by_package(self, package_id):<DEDENT>
return<EOL>
Gets an ``InstallationList`` corresponding to the given ``Package``.

        In plenary mode, the returned list contains all of the
        installations for the specified package, in the order of the
        list, including duplicates, or an error results if an ``Id`` in
        the supplied list is not found or inaccessible. Otherwise,
        inaccessible ``Installations`` may be omitted from the list and
        may present the elements in any order including returning a
        unique set.

        :param package_id: ``Id`` of a ``Package``
        :type package_id: ``osid.id.Id``
        :return: the returned ``Installation`` list
        :rtype: ``osid.installation.InstallationList``
        :raise: ``NullArgument`` -- ``package_id`` is ``null``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``PermissionDenied`` -- authorization failure

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