def is_leaf(tree):
    "Returns True if the given tree's list of branches is empty, and False\n    otherwise.\n    "
    return (not branches(tree))
Returns True if the given tree's list of branches is empty, and False
otherwise.
def is_leaf(tree):
    "Returns True if the given tree's list of branches is empty, and False\n    otherwise.\n    "
    return (not branches(tree))