many_combinations.go

switch {
case olderr != nil && newerr != nil:
	return diff, fmt.Errorf("reading both source, %v", olderr)
case olderr != nil:
	return diff, fmt.Errorf("reading old source, %v", olderr)
case newerr != nil:
	return diff, fmt.Errorf("reading new source, %v", newerr)
default:
	return diff, nil
}

read_til_eof.go

for {
	line, err := rd.ReadBytes('\n')
	switch err {
	case io.EOF:
		return nil
	case nil:
	default:
		return err
	}
	total += uint64(len(line) + 1)
	lines <- line
}