def set_published_date(self, published_date=None):
if published_date is None:<EOL><INDENT>raise NullArgument()<EOL><DEDENT>metadata = Metadata(**settings.METADATA['<STR_LIT>'])<EOL>if metadata.is_read_only():<EOL><INDENT>raise NoAccess()<EOL><DEDENT>if self._is_valid_input(published_date, metadata, array=False):<EOL><INDENT>self._my_map['<STR_LIT>'] = published_date  <EOL><DEDENT>else:<EOL><INDENT>raise InvalidArgument()<EOL><DEDENT>
Sets the published date.

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

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