text: import { useState } from 'react';
  import SetupForm from './SetupForm';
  import TimerView from './TimerView';
  
  const ComplexTimer = () => {
    const [timerSetup, setTimerSetup] = useState(null);
  
    const onStart = (setup) => setTimerSetup(setup);
  
    const onReset = () => setTimerSetup(null);
  
    return (
      !timerSetup ? (
        <SetupForm onStart={onStart} />
      ) : (
        <TimerView setup={timerSetup} onBack={onReset} />
      )
    );
  };
  
  export default ComplexTimer;
  