docs: def add_step(self, setting, duration):
          """
          Adds steps to a program.
          :param setting: Current, Wattage or Resistance, depending on program mode.
          :param duration: Length of step in seconds.
          :return: None
          """
          if len(self._prog_steps) < 10:
              self._prog_steps.append(ProgramStep(self, setting, duration))
          else:
              raise IndexError("Maximum of 10 steps are allowed")