def set_url(self, url=None):
<EOL>if url is not None:<EOL><INDENT>self._payload.set_url(url)<EOL><DEDENT>
Sets the url.

        arg:    url (string): the new copyright
        raise:  InvalidArgument - ``url`` is invalid
        raise:  NoAccess - ``Metadata.isReadOnly()`` is ``true``
        raise:  NullArgument - ``url`` is ``null``
        *compliance: mandatory -- This method must be implemented.*