def wantOne(self, **kw):
        """
        Add a character attribute to a copy of this formatting state.

        @param **kw: An optional attribute name and value can be provided with
            a keyword argument.

        @return: A formatting state instance with the new attribute.

        @see: L{DefaultFormattingState._withAttribute}.
        """
        k, v = kw.popitem()
        return self._withAttribute(k, v)

        Add a character attribute to a copy of this formatting state.

        @param **kw: An optional attribute name and value can be provided with
            a keyword argument.

        @return: A formatting state instance with the new attribute.

        @see: L{DefaultFormattingState._withAttribute}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/insults/helper.py