student@student-VirtualBox:~$ charms.reactive --help
Traceback (most recent call last):
  File "/home/student/.local/bin/charms.reactive", line 7, in <module>
    from charms.reactive import bus  # noqa
  File "/home/student/.local/lib/python2.7/site-packages/charms/reactive/__init__.py", line 22, in <module>
    from .relations import *  # noqa
  File "/home/student/.local/lib/python2.7/site-packages/charms/reactive/relations.py", line 252
    class RelationBase(RelationFactory, metaclass=AutoAccessors):
                                                 ^
SyntaxError: invalid syntax