def METHOD_NAME(camera):
    """Converts `camera` (*e.g.* 'b0') to an integer in a simple but ultimately
    arbitrary way.
    Parameters
    ----------
    camera : :class:`str`
        Camera name.
    Returns
    -------
    :class:`int`
        An arbitrary integer, though in the range [0, 29].
    """
    return 'brz'.index(camera[0]) * 10 + int(camera[1])