def _getline(cube):
    """
    Read a line from cube file.

    First field is an int and the remaining fields are floats.
    
    Parameters
    ----------
    cube : TextIO
        The cubefile from which the line is read.

    Returns
    -------
    line : tuple
        First entry is an int, and the rests are floats.
    """
    line = cube.readline().strip().split()
    return int(line[0]), map(float, line[1:])