NewStdReader creates a reader for consuming a stdio stream.

StdCopy will de-multiplex `src`, assuming that it contains two streams, previously multiplexed together using a StdWriter instance.

Stderr represents standard error steam type.

Stdin represents standard input stream type.

Stdout represents standard output stream type.

Systemerr represents errors originating from the system that make it into the multiplexed stream.

StdHeader is a descriptor for a stdio stream frame It gets used in conjunction with StdReader.