human
Complete the below
def _postorder_traverse(root, get_children):

    ''''Traverse a tree in depth-first post-order (children before parent).'
    '''
assistant
#Here is the Python code you requested.
    def dfs(elem):
        for v in get_children(elem):
            for u in dfs(v):
                (yield u)
        (yield elem)
    for elem in dfs(root):
        (yield elem)