Trailing commas are a bit subtle and readers of the code may think it was a mistake. (We spend more time reading code later than writing it in the first place.

Trailing commas are a bit subtle and readers of the code may think it was a mistake. (We spend more time reading code later than writing it in the first place.) Even Python removed one of its most prominent cases of this, the print command. In Python 2.x you could have a trailing comma after a print to omit the new-line but Python 3's print() function requires print('something', end=' ') to be more explicit about it.