text: window.onload = () => {
      const simpleFunction = document.getElementById('simple-function');
      const functionParameters = document.getElementById('function-parameters');
      const functionReturn = document.getElementById('function-return');
      const functionCalls = document.getElementById('function-calls');
        functionCalls.onclick = () => {
          simpleFunction();
          functionParameters();
          functionReturn();
        }
      }
        function simpleFunction () {
          console.log('functions should consist of statements designed to perform a single task.');
          simpleFunction.textContent = 'functions should consist of statements designed to perform a single task.';
          }
       function functionParameters (input) {
          console.log(input);
          functionParameters.textContent = input;
          }
       function functionReturn () {
          functionReturn.textContent = 'Many functions return values.';
          return 'Many functions return values.';
          }
  