For write streams, force the buffered data to be immediately written to the output,
without to wait to fill the internal buffer.
For read streams, discard all currently buffered data, and advance the
reported file position to that of the underlying stream. This does not
read new data, and does not perform any seeks.
Force flushing of buffered data.
For write streams, force the buffered data to be immediately written to the output, without to wait to fill the internal buffer.
For read streams, discard all currently buffered data, and advance the reported file position to that of the underlying stream. This does not read new data, and does not perform any seeks.