The format of map seems off. Coming from JS, all the functions come second. I think this approach is superior. Currently: map(lambda x: chr(ord('a')+x), range(26)) # ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'] But I think this reads better: map(range(26), lambda x: chr(ord('a')+x)) Currently that results in: TypeError: argument 2 to map() must support iteration Also, how are we to tell what supports map()? Any iterable should be able to map via: range(26).map(lambda x: chr(ord('a')+x))) While the line length is the same, I think the latter is much more readable, and the member method avoids parameter order confusion For the global map(), having the iterable first also increases reliability because the lambda function is highly variable in length, where as parameter names are generally shorter than even the longest lambda expression. More readable: IMHO: map(in, lambda x: chr(ord('a')+x)) out = map(out, lambda x: chr(ord('a')+x)) out = map(out, lambda x: chr(ord('a')+x)) Less readable (I have to parse the lambda): map(lambda x: chr(ord('a')+x), in) out = map(lambda x: chr(ord('a')+x), out) out = map(lambda x: chr(ord('a')+x), out) But I contend: range(26).map(lambda x: chr(ord('a')+x))) is superior to all.