def locateResponder(self, name):
        """
        Locate a callable to invoke when executing the named command.

        @return: a function with the name C{"amp_" + name} on the same
            instance, or None if no such function exists.
            This function will then be called with the L{AmpBox} itself as an
            argument.

        @param name: the normalized name (from the wire) of the command.
        @type name: C{bytes}
        """
        fName = nativeString(self.baseDispatchPrefix + name.upper())
        return getattr(self, fName, None)

        Locate a callable to invoke when executing the named command.

        @return: a function with the name C{"amp_" + name} on the same
            instance, or None if no such function exists.
            This function will then be called with the L{AmpBox} itself as an
            argument.

        @param name: the normalized name (from the wire) of the command.
        @type name: C{bytes}
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/protocols/amp.py