code: func (f *Fetcher) NextLogEntry() (*logpb.LogEntry, error) {
  	var le *logpb.LogEntry
  	if f.fetchErr == nil {
  		resp := <-f.logC
  		if resp.err != nil {
  			f.fetchErr = resp.err
  		}
  		if resp.log != nil {
  			le = resp.log
  		}
  	}
  	return le, f.fetchErr
  }
docs: // NextLogEntry returns the next buffered LogEntry, blocking until it becomes
  // available.
  //
  // If the end of the log stream is encountered, NextLogEntry will return
  // io.EOF.
  //
  // If the Fetcher is cancelled, a context.Canceled error will be returned.