def bytes_to_str(num, suffix='B'):
    """
    Convert number to a human readable string with decimal prefix.

    :param float num: Value in given unit.
    :param str suffix: Unit suffix. Defaults to 'B'.
    :returns: Human readable string with decimal prefixes.
    :rtype: str
    """
    for unit in ('', 'K', 'M', 'G'):
        if abs(num) < 1024.0:
            return f'{num:3.1f}{unit}{suffix}'
        num /= 1024.0
    return f'{num:.1f}T{suffix}'