forEach method
Implementation
void forEach(LineAction stdout, {LineAction stderr = devNull}) {
/// This is somewhat dodgy as we essentially replace the progresses
/// stdout and stderr handlers that we setup when the
/// progress was originally created. We need to find
/// a more self consistent approach as this behavour can endup
/// with the user getting inconsistent results
/// e.g. they essentially pass stdout and stderr twice.
_includeStdout = true;
if (stderr != devNull) {
_includeStderr = true;
}
_processUntilComplete(stdout, stderr: stderr);
}