Traceback (most recent call last):
  File "hello_world.py", line 18, in ?
  File "/usr/lib/python2.4/site-packages/freeswitch.py", line 64, in get_variable
    def get_variable(*args): return _freeswitch.SessionContainer_get_variable(*args)
TypeError: SessionContainer_get_variable() takes exactly 3 arguments (2 given)