Convert comma separated list of column names and ranges to indices.

    Parameters
    ----------
    areas : str
        A string containing a sequence of column ranges (or areas).

    Returns
    -------
    cols : list
        A list of 0-based column indices.

    Examples
    --------
    >>> _range2cols('A:E')
    [0, 1, 2, 3, 4]
    >>> _range2cols('A,C,Z:AB')
    [0, 2, 25, 26, 27]

def _range2cols(areas):
    """
    Convert comma separated list of column names and ranges to indices.

    Parameters
    ----------
    areas : str
        A string containing a sequence of column ranges (or areas).

    Returns
    -------
    cols : list
        A list of 0-based column indices.

    Examples
    --------
    >>> _range2cols('A:E')
    [0, 1, 2, 3, 4]
    >>> _range2cols('A,C,Z:AB')
    [0, 2, 25, 26, 27]
    """
    cols = []

    for rng in areas.split(","):
        if ":" in rng:
            rng = rng.split(":")
            cols.extend(lrange(_excel2num(rng[0]), _excel2num(rng[1]) + 1))
        else:
            cols.append(_excel2num(rng))

    return cols