def _set_separator(ticklabels, separator):
    """
    Set the decimal separator. Note that this is a 'private' function, so
    you can set the decimal separator directly in plotting functions.
    """
    if separator == '.':
        bands_sep = ticklabels
    else:
        bands_sep = []
        for item in ticklabels:
            decimal_number_format = item.replace('.', separator)
            bands_sep.append(decimal_number_format)
    return bands_sep
