a = [[1, 2, 3], [4, 5, 6], [7, 8, 9]] for x in a: print(max(x))
>>> def find_max_in_tree(lst): ... out = [] ... for i in lst: ... if type(i) is not list: ... out.append(i) ... else: ... out.append(find_max_in_tree(i)) ... return (out and max(out)) or None ... >>> lst = [[1, 2, 3, [4, 5, 6], [7, 8, 9]], [1, 2, 3, [12]]] >>> >>> find_max_in_tree(lst) 12 >>> find_max_in_tree([]) >>> find_max_in_tree([1]) 1 >>> find_max_in_tree([1, 2, 1]) 2 >>> find_max_in_tree([1, 2, [4], 1]) 4 >>> find_max_in_tree([1, 2, [1], 1]) 2 >>>