@abc.abstractmethod<EOL><INDENT>def get_bin_hierarchy_session(self):<DEDENT>
return<EOL>
Gets the bin hierarchy traversal session.

        :return: ``a BinHierarchySession``
        :rtype: ``osid.resource.BinHierarchySession``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``Unimplemented`` -- ``supports_bin_hierarchy()`` is ``false``

        *compliance: optional -- This method must be implemented if
        ``supports_bin_hierarchy()`` is ``true``.*