Converts a string into its encoded positive integer (greater zero) or throws an exception.

def to_positive_multiple_of_10(string):
    """Converts a string into its encoded positive integer (greater zero) or throws an exception."""
    try:
        value = int(string)
    except ValueError:
        msg = '"%r" is not a positive multiple of 10 (greater zero).' % string
        raise argparse.ArgumentTypeError(msg)
    if value <= 0 or value % 10 != 0:
        msg = '"%r" is not a positive multiple of 10 (greater zero).' % string
        raise argparse.ArgumentTypeError(msg)
    return value