@abc.abstractmethod<EOL><INDENT>def set_timestamp(self, timestamp):<DEDENT>
pass<EOL>
Sets the timestamp.

        :param timestamp: the new timestamp
        :type timestamp: ``osid.calendaring.DateTime``
        :raise: ``InvalidArgument`` -- ``timestamp`` is invalid
        :raise: ``NoAccess`` -- ``Metadata.isReadOnly()`` is ``true``
        :raise: ``NullArgument`` -- ``timestamp`` is ``null``

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