I’ve been confused of list comprehension in Python, although its shorthand doing for loop is very convenient. I’m not sure if what’s in the
join() function’s parameter below is list comprehension since usually you put
 around to show it’s a list comprehension.
My question: What’s the type of iterable produced by
str(x) for x in res[::-1] in
join() below? Thanks.
''.join( str(x) for x in res[::-1] )
This is a generator expression, which itself is an iterable.
The square brackets could still be added, however. Refer Joining strings. Generator or list comprehension?