title: Using custom Xon/Xoff characters with pyserial
body: <p>Is it possible to redefine the "constants" serial.XON and serial.XOFF.  I'm assuming that if the underlying uart supports xon/xoff flow control in the hardware then pyserial passes these constants down the driver chain.  I know I can get around this by turning off xon/xoff flow control and processing the chars myself.  I already do that to wait for the Xon char which my application requires.  Which is interfacing to weird serial protocols on cnc machines.  But I would like the uart to do it if possible.  CNC machines are very sensitive to buffer overflows.  Thanks.</p>