function spreadsheetColumnLabel(index) {
  var dividend = index + 1;
  var columnLabel = '';
  var modulo;

  while (dividend > 0) {
    modulo = (dividend - 1) % COLUMN_LABEL_BASE_LENGTH;
    columnLabel = String.fromCharCode(65 + modulo) + columnLabel;
    dividend = parseInt((dividend - modulo) / COLUMN_LABEL_BASE_LENGTH, 10);
  }

  return columnLabel;
}
Generates spreadsheet-like column names: A, B, C, ..., Z, AA, AB, etc.

@param {Number} index Column index.
@returns {String}