Python 2 does, Python 3 does not: > TabError: inconsistent use of tabs and spaces in indentation Note for pedant: Yes, you can mix tabs and spaces in Python3,

Python 2 does, Python 3 does not: > TabError: inconsistent use of tabs and spaces in indentation Note for pedant: Yes, you can mix tabs and spaces in Python3, but only if you do it absolutely consistently for the block and all sub-block.