text: class Test { 
      constructor() {
  
      }
  }
  
  function testFunction() {
      console.log(this);
  }
  
  const test = new Test();
  test.testFunction = testFunction;
  
  //this rulls in declarative functions
  //this depends on where function is called
  //this points to global object
  testFunction();
  
  //this points to test object
  test.testFunction();
  
  //arrow function is declared on window object
  test.bar = () => console.log(this);
  test.bar();