more-itertools: Error in more.py during pytest in Python 2.7

I received this error in version 6.0 (released just now in PyPi) when running pytest which depends on more-itertools. I am using python 2.7

def _collate(*iterables, key=lambda a: a, reverse=False):
                           ^
SyntaxError: invalid syntax

Edited to add: For people finding this issue from Google, the issue is with Python 2.7. For a version more more-itertools that works with that version of Python, pip install more_itertools==5.0.0.