code: def get_type(self, index):
  
          
          if index < 0 or index >= len(self._types):
              raise ValueError("Index for getting order parameter type"
                               " out-of-bounds!")
          return self._types[index]
docs: Return type of order parameter at the index provided and
          represented by a short string.
  
          Args:
              index (int): index of order parameter for which type is
                  to be returned.
          Returns:
              str: OP type.