cclient takes one optional command line argument, the server port number
The default is port 8000.  

$ python cclient.py 6340
Type command + data, h for help, RETURN to exit: h
At the prompt, type one-character command followed by data
 h (or unrecognized cmd): help, print commands, data ignored
 ?: send uninterpreted data (string) to server
 !: send string, then close connection without reading server response
 z: zero output always (open loop), data ignored
 k: output is scaled input, data is gain
 f: first order low-pass filter, data is corner frequency
 s: second order low-pass filter, data is resonant frequency
 t: transfer function, data is b coeffs, comma, then a coeffs
 m: scale factors, data are k0 k1, usually 0 or 1
 p: read from file in params.h format, data is filename
 x (or RETURN, empty line): exit, data ignored