Compare the extant river with the given name to the passed JSON. The
    command will exit with a return code of 0 if the named river is configured
    as specified, and 1 otherwise.

def compare(args):
    """
    Compare the extant river with the given name to the passed JSON. The
    command will exit with a return code of 0 if the named river is configured
    as specified, and 1 otherwise.
    """
    data = json.load(sys.stdin)
    m = RiverManager(args.hosts)
    if m.compare(args.name, data):
        sys.exit(0)
    else:
        sys.exit(1)