def _parse_detector(detector):
    """
    Check and fix detector name strings.

    Parameters
    ----------
    detector : `str`
        The detector name to check.
    """
    oklist = ['n0', 'n1', 'n2', 'n3', 'n4', 'n5', 'n6', 'n7', 'n8', 'n9',
              'n10', 'n11']
    altlist = [str(i) for i in range(12)]
    if detector in oklist:
        return detector
    elif detector in altlist:
        return 'n' + detector
    else:
        raise ValueError('Detector string could not be interpreted')