How to read encoder ticks from arduino with pyserial

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I am using a arduino due to read two encoders for wheel position. How do I send those number strings to the pyserial and have pyserial read it as left, right wheel(for ros Odom)? I am not all that good at programming, so how would I setup up the sending side and the receiving side? The encoders resolution is 4096 tick/rev and full motor speed is 3k rpm. I am using the output for the differential_drive ros package. http://www.ros.org/wiki/differential_drive