human
Complete this python program:
def _AddPrivateHelperMethods(cls):
assistant
#Here is the Python code you requested.

    """Adds implementation of private helper methods to cls.
    """
    def Modified(self):
        'Sets    the    _cached_byte_size_dirty    bit    to    true,\n                and    propagates    this    to    our    listener    iff    this    was    a    state    change.\n                '
        if (not self._cached_byte_size_dirty):
            self._cached_byte_size_dirty = True
            self._listener_for_children.dirty = True
            self._is_present_in_parent = True
            self._listener.Modified()
    cls._Modified = Modified
    cls.SetInParent = Modified