I'd desugar it like this: >>> lookup = {} >>> for (x, lookup[x]) in ('ab', 'cd', 'ef'): ... pass ... >>> lookup {'a': 'b', 'c': 'd

I'd desugar it like this: >>> lookup = {} >>> for (x, lookup[x]) in ('ab', 'cd', 'ef'): ... pass ... >>> lookup {'a': 'b', 'c': 'd', 'e': 'f'} This makes is much more clear that there is just a double assignment, and that comprehension are pretty close to regular `for` statement. (this was a great example btw -- I write python3 a lot, and I was staring at it for a long time before Icould figure it out)