Write calibration set to file

def write_calibration(calib, f, loc):
    """Write calibration set to file"""
    for i, node in enumerate(
        [p + '_' + s for p in ['pos', 'dir'] for s in 'xyz']):
        h5loc = loc + '/' + node
        ca = f.get_node(h5loc)
        ca.append(calib[:, i])

    du = f.get_node(loc + '/du')
    du.append(calib[:, 7].astype('u1'))

    floor = f.get_node(loc + '/floor')
    floor.append(calib[:, 8].astype('u1'))

    t0 = f.get_node(loc + '/t0')
    t0.append(calib[:, 6])

    if loc == "/hits":
        time = f.get_node(loc + "/time")
        offset = len(time)
        chunk_size = len(calib)
        time[offset - chunk_size:offset] += calib[:, 6]