def append(self, child):
"""overridden to detect problems easily"""
assert child not in self.parents()
VNode.append(self, child)
def append(self, child):
"""overridden to detect problems easily"""
assert child not in self.parents()
VNode.append(self, child)
def __init__(self, id=None, klass=None):
VNode.__init__(self, id)
self.klass = klass
def __init__(self, id=None, klass=None):
VNode.__init__(self, id)
self.klass = klass
