text: console.log("Hello world!");
  
  /*----------------------------------------------------------------------------*/
  const name1 = "Javascript";
  {
      let name2 = "Javascript"; // "let" defines a variable within scope ...
      var name3 = "Hamster";
  }
  const name4 = "Hamster";
  
  var name2 = "Java"; // Comment this out, then "name2" is undefined
  name3 = "Ham"; // var name3 = "Ham" will return an error
  
  console.log(name1 + " to " + name2 + " is like " + name3 + " to " + name4 + ".");
  /*----------------------------------------------------------------------------*/
  function factorial(a){
      a = Math.round(a);
      if(a <= 0) {
          return 1;
      }
      return a*factorial(a-1);
  }
  
  console.log(factorial(5));
  
  let myfun = factorial;
  console.log(myfun(5));
  
  let myfun2 = (a)=>{
      a = Math.round(a);
      if(a <= 0) {
          return 1;
      }
      return a*factorial(a-1)
  };
  console.log(myfun2(7));
  
  /*-------------------------------------------------------------------------------*/
  let X = [...Array(10).keys()];
  let Y = X.map((x)=>(x*x));
  let Z = Y.reduce((y1,y2)=>y1+y2);
  console.log(X);
  console.log(Y);
  console.log(Z);