parameters: (self, serviceName, username)
docstring: Called to build a user subscription message for a bot. Expects any
          return value that can later serve as a parameter to send_message.
docstring_summary: Called to build a user subscription message for a bot. Expects any
          return value that can later serve as a parameter to send_message.
docstring_tokens: Called to build a user subscription message for a bot . Expects any return value that can later serve as a parameter to send_message .
function: def on_user_subscribe(self, serviceName, username):
          '''
          Called to build a user subscription message for a bot. Expects any
          return value that can later serve as a parameter to send_message.
          '''
          raise NotImplementedError
function_tokens: def on_user_subscribe ( self , serviceName , username ) : raise NotImplementedError