text: const screen = document.querySelector(".main__screen");
  
  // Set screen result, mostly used after equals button or some variations as square root, that when pressed only shows the final result.
  function setScreen(value) {
      screen.value = value;
  }
  
  // Update screen constantly, when the expression still being formed, the buttons value are appended and shows in the screen;
  function appendScreen(value) {
      screen.value += value;
  }
  
  // Get the screen value and returns;
  function getScreen() {
      return screen.value;
  }
  
  // If the screen value still an expression, then the function evaluate the text and return a number;
  function getEvaluatedScreen() {
      return eval(screen.value);
  }
  
  // Set screen to an error message, used when the expression has semantic errors;
  function errorScreen() {
      screen.value = "error ಠ_ಠ";
  }
  
  // Clear the Screen.
  function clearScreen() {
      screen.value = ''
  }
  
  // Add an event listener to the Clear button, when pressed the screen turns to none value;
  const clear = document.querySelector(".c-btn");
  
  clear.addEventListener('click', function() {
      clearScreen();
      clearAuxScreen();
  });
  