code: def process (self, input_symbol):
  
          '''This is the main method that you call to process input. This may
          cause the FSM to change state and call an action. This method calls
          get_transition() to find the action and next_state associated with the
          input_symbol and current_state. If the action is None then the action
          is not called and only the current state is changed. This method
          processes one complete input symbol. You can process a list of symbols
          (or a string) by calling process_list(). '''
  
          self.input_symbol = input_symbol
          (self.action, self.next_state) = self.get_transition (self.input_symbol, self.current_state)
          if self.action is not None:
              self.action (self)
          self.current_state = self.next_state
          self.next_state = Nonf process (self, input_symbol):
  
          '''This is the main method that you call to process input. This may
          cause the FSM to change state and call an action. This method calls
          get_transition() to find the action and next_state associated with the
          input_symbol and current_state. If the action is None then the action
          is not called and only the current state is changed. This method
          processes one complete input symbol. You can process a list of symbols
          (or a string) by calling process_list(). '''
  
          self.input_symbol = input_symbol
          (self.action, self.next_state) = self.get_transition (self.input_symbol, self.current_state)
          if self.action is not None:
              self.action (self)
          self.current_state = self.next_state
          self.next_state = None
docs: This is the main method that you call to process input. This may
          cause the FSM to change state and call an action. This method calls
          get_transition() to find the action and next_state associated with the
          input_symbol and current_state. If the action is None then the action
          is not called and only the current state is changed. This method
          processes one complete input symbol. You can process a list of symbols
          (or a string) by calling process_list().