missing parenthesis in test/unit/tutorial.py

stem git:(master) : ./run_tests.py 
Traceback (most recent call last):
  File "./run_tests.py", line 45, in <module>
    import test.unit.tutorial
  File "/Users/sathya/Documents/stem/test/unit/tutorial.py", line 66
    for bw_value in sorted(bw_to_relay.keys(), reverse = True:
                                                             ^
SyntaxError: invalid syntax