for {
		line, err := scanner.ReadString('\n')
		if err == io.EOF {
			break
		}

		fields := strings.Fields(line)
		if len(fields) != expectedNumFieldsPerLine {
			// ignore incorrect lines.
			continue
		}

		// Freq should be an integer.
		if _, err := strconv.Atoi(fields[4]); err != nil {
			return nil, err
		}

		// Pass should be an integer.