'Like a call to update(), but applied recursively for all ancestors.
Note: it is important that this happens from the root downward so that \'parent\' visit
counts are correct.'

def update_recursive(self, leaf_value, c_puct):

    if self._parent:
        self._parent.update_recursive(leaf_value, c_puct)
    self.update(leaf_value, c_puct)
