I have this function that returns the hex code of the background color of the pointed cell. Its ok so far but I need this to be reactive to changes in the background color of the pointed cell. As it is, every time the background color of the cell changes I have to call again the function in order to it takes notice of that the background color has changed. There is any way to make this function reactive to changes in the background of thhe pointed cell?

```
  function color(input) {
  var ss = SpreadsheetApp.getActiveSpreadsheet(); 
  var activeRange = SpreadsheetApp.getActiveRange();
  var formula = activeRange.getFormula();
  var address = formula.substr(7,2);

  var cell = ss.getRange(address); 
  var result = cell.getBackground(); 
  return result;
}

```