Converts input and returns the result of the conversion.

Source

List<int> convert(String input) {
  if (input.isEmpty) return new Uint8List(0);
  int length = input.length;
  if (length % 4 != 0) {
    throw new FormatException("Invalid length, must be multiple of four",
                              input, length);
  }
  var decoder = new _Base64Decoder();
  Uint8List buffer = decoder.decode(input, 0, input.length);
  decoder.close(input, input.length);
  return buffer;
}