code: def set_input(self, p_name, value):
          
          name = self.python_names.get(p_name)
          if p_name is None or name not in self.get_input_names():
              raise ValueError('Invalid input "{}"'.format(p_name))
          self.step_inputs[name] = value
docs: Set a Step's input variable to a certain value.
  
          The value comes either from a workflow input or output of a previous
              step.
  
          Args:
              name (str): the name of the Step input
              value (str): the name of the output variable that provides the
                  value for this input.
  
          Raises:
              ValueError: The name provided is not a valid input name for this
                  Step.