def get(self, instance, methodName, default=_nodefault):
        """
        Retrieve an exposed method with the given name from the given instance.

        @raise UnexposedMethodError: Raised if C{default} is not specified and
        there is no exposed method with the given name.

        @return: A callable object for the named method assigned to the given
        instance.
        """
        method = getattr(instance, methodName, None)
        exposedThrough = getattr(method, 'exposedThrough', [])
        if self not in exposedThrough:
            if default is self._nodefault:
                raise UnexposedMethodError(self, methodName)
            return default
        return method

        Retrieve an exposed method with the given name from the given instance.

        @raise UnexposedMethodError: Raised if C{default} is not specified and
        there is no exposed method with the given name.

        @return: A callable object for the named method assigned to the given
        instance.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/_element.py