ByteConversionSink startChunkedConversion(Sink<String> sink)

Starts a chunked conversion.

The returned sink serves as input for the long-running conversion. The given sink serves as output.

Source 

ByteConversionSink startChunkedConversion(Sink<String> sink) {
  if (sink is StringConversionSink) {
    return new _Utf8Base64EncoderSink(sink.asUtf8Sink(false), _urlSafe);
  }
  return new _AsciiBase64EncoderSink(sink, _urlSafe);
}