def __str__(self):
        """
        Return a string representation of this C{Deferred}.
        """
        cname = self.__class__.__name__
        result = getattr(self, 'result', _NO_RESULT)
        myID = id(self)
        if self._chainedTo is not None:
            result = ' waiting on Deferred at 0x%x' % (id(self._chainedTo),)
        elif result is _NO_RESULT:
            result = ''
        else:
            result = ' current result: %r' % (result,)
        return "<%s at 0x%x%s>" % (cname, myID, result)

        Return a string representation of this C{Deferred}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/defer.py