def plot_ranges_from_cli(opts):
    """Parses the mins and maxs arguments from the `plot_posterior` option
    group.

    Parameters
    ----------
    opts : ArgumentParser
        The parsed arguments from the command line.

    Returns
    -------
    mins : dict
        Dictionary of parameter name -> specified mins. Only parameters that
        were specified in the --mins option will be included; if no parameters
        were provided, will return an empty dictionary.
    maxs : dict
        Dictionary of parameter name -> specified maxs. Only parameters that
        were specified in the --mins option will be included; if no parameters
        were provided, will return an empty dictionary.
    """
    mins = {}
    for x in opts.mins:
        x = x.split(':')
        if len(x) != 2:
            raise ValueError("option --mins not specified correctly; see help")
        mins[x[0]] = float(x[1])
    maxs = {}
    for x in opts.maxs:
        x = x.split(':')
        if len(x) != 2:
            raise ValueError("option --maxs not specified correctly; see help")
        maxs[x[0]] = float(x[1])
    return mins, maxs