def _descendents(node, children=None):
    children = (children or list())
    children.append(node)
    for child in node.children(filter=None):
        _descendents(child, children)
    return children
def _descendents(node, children=None):
    children = (children or list())
    children.append(node)
    for child in node.children(filter=None):
        _descendents(child, children)
    return children