#6718: fix example.

Doc/library/socketserver.rst

@@ -464,7 +464,7 @@ This is the client side::
    import socket
    import sys
 
-   HOST, PORT = "localhost"
+   HOST, PORT = "localhost", 9999
    data = " ".join(sys.argv[1:])
 
    # SOCK_DGRAM is the socket type to use for UDP sockets