code: def set_input(self,filename,pass_to_command_line=True):
      
      self.__input = filename
      if pass_to_command_line:
        self.add_var_opt('input', filename)
      self.add_input_file(filename)
docs: Add an input to the node by adding a --input option.
      @param filename: option argument to pass as input.
      @bool pass_to_command_line: add input as a variable option.