def unpickleMethod(im_name, im_self, im_class):
    """
    Support function for copy_reg to unpickle method refs.

    @param im_name: The name of the method.
    @type im_name: native L{str}

    @param im_self: The instance that the method was present on.
    @type im_self: L{object}

    @param im_class: The class where the method was declared.
    @type im_class: L{types.ClassType} or L{type} or L{None}
    """
    if im_self is None:
        return getattr(im_class, im_name)
    try:
        methodFunction = _methodFunction(im_class, im_name)
    except AttributeError:
        log.msg("Method", im_name, "not on class", im_class)
        assert im_self is not None, "No recourse: no instance to guess from."
        # Attempt a last-ditch fix before giving up. If classes have changed
        # around since we pickled this method, we may still be able to get it
        # by looking on the instance's current class.
        if im_self.__class__ is im_class:
            raise
        return unpickleMethod(im_name, im_self, im_self.__class__)
    else:
        if _PY3:
            maybeClass = ()
        else:
            maybeClass = tuple([im_class])
        bound = types.MethodType(methodFunction, im_self, *maybeClass)
        return bound

    Support function for copy_reg to unpickle method refs.

    @param im_name: The name of the method.
    @type im_name: native L{str}

    @param im_self: The instance that the method was present on.
    @type im_self: L{object}

    @param im_class: The class where the method was declared.
    @type im_class: L{types.ClassType} or L{type} or L{None}
    
stackoverflow/venv/lib/python3.6/site-packages/twisted/persisted/styles.py