text: function add1(x, y) {
    return x + y;
  }
  
  const add2 = (x, y) => {
    return x + y;
  };
  
  const add3 = (x, y) => x + y;
  
  const add4 = (x, y) => (x + y);
  
  function not1(x) {
    return !x;
  }
  
  const not2 = x => !x;
  