def __set__(self, oself, value):
        """
        Set the C{self.attributeName} property of I{oself}.
        """
        original = getattr(oself, self.originalAttribute)
        setattr(original, self.attributeName, value)

        Set the C{self.attributeName} property of I{oself}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/python/components.py