Maya node traversal example

def traverse(node):
    print ' ' * traverse.level + ' ' + node
    children = cmds.listRelatives(node, children=True, fullPath=True)
    if children:
        for child in children:
            traverse.level += 1
            traverse(child)
            traverse.level -= 1

traverse.level = 1
nodes = cmds.ls('|*')
for node in nodes:
    traverse(node)