When runned with python lm.py with python 3.5 get a syntax error

[sabatlisbon]

When I run lm.py i get an syntax error. I tried with python 2.6 and python 3.5. I get the error with 3.5.

$ python lm.py
File "lm.py", line 346
raise KeyError, str(key) + " not in store keys"
^
SyntaxError: invalid syntax