code: def direction(self, direction):
          
          if not isinstance(direction, str):
              raise TypeError("direction must be of type str")
  
          accepted_values = ['i', 'x', 'y', 'z', 's', 'c']
          if direction not in accepted_values:
              raise ValueError("must be one of: {}".format(accepted_values))
  
          self._direction = direction
docs: set the direction