function columnIndexToLabel(column) {
  var result = '';

  while (column >= 0) {
    result = String.fromCharCode(column % COLUMN_LABEL_BASE_LENGTH + 97) + result;
    column = Math.floor(column / COLUMN_LABEL_BASE_LENGTH) - 1;
  }

  return result.toUpperCase();
}
Convert column index to label.

@param {Number} column Column index.
@returns {String} Returns column label (eq. 'ABB', 'CNQ').