Report sample rate after measurement

    signal.signal(signal.SIGQUIT, graceful_exit)

    korad = KA320(port, channel)

    start_ts = time.time()

    if filename is not None:

        output_handle = open(filename, "w+")

    else:

    else:

        print(f"Starting data acquisition. Press Ctrl+C to stop.")

    start_ts = time.time()

    print("# Device: " + korad.get_id(), file=output_handle)

    print("# Timestamp Voltage Current", file=output_handle)

    while not terminate_measurement:

    output = output_handle.read()

    output_handle.close()

    # exclude header

    output_len = len(output.splitlines()) - 2

    print(

        f"Logged {output_len:d} samples in {ts - start_ts:.0f} seconds (mean sample rate: {output_len / (ts - start_ts) :.1f} Hz)"

    )

    return output