Google Sheets function that returns the hex code for the background colour of a cell

getHex.gs

/**
 * getHex.gs
 * =getHex(cell("address",A1)) returns hex code for background colour of cell A1
 * taken from https://stackoverflow.com/questions/28962526/google-spreadsheets-sort-filter-by-background-fill
 */

function getHex(input) {
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var cell = ss.getRange(input);
  var result = cell.getBackground();
  return result
}