def _append_node(self, child):
        """append a child, linking it in the tree"""
        # pylint: disable=no-member; depending by the class
        # which uses the current class as a mixin or base class.
        # It's rewritten in 2.0, so it makes no sense for now
        # to spend development time on it.
        self.body.append(child)
        child.parent = self
def _append_node ( self , child ) : self . body . append ( child ) child . parent = self
append a child, linking it in the tree