In the Data Structures section of the Tutorial there are examples of nested list comprehensions that include list literals where elements are written without spaces after commas (`[1,2,3]` instead `[1, 2, 3]`). 

This is a trivial problem but since this is a tutorial for newcomers (and one of the previous parts of this tutorial explicitly says that the spaces should be present after commas, and in other parts of the tutorial they are consistently put there) I think this deserves to be fixed.