Return min and max digital values for each format type.
    Accepts lists.

    Parmeters
    ---------
    fmt : str, or list
        The wfdb dat format, or a list of them.

def _digi_bounds(fmt):
    """
    Return min and max digital values for each format type.
    Accepts lists.

    Parmeters
    ---------
    fmt : str, or list
        The wfdb dat format, or a list of them.

    """
    if isinstance(fmt, list):
        return [_digi_bounds(f) for f in fmt]

    if fmt == '80':
        return (-128, 127)
    elif fmt == '212':
        return (-2048, 2047)
    elif fmt == '16':
        return (-32768, 32767)
    elif fmt == '24':
        return (-8388608, 8388607)
    elif fmt == '32':
        return (-2147483648, 2147483647)