PyWPS-Demo comes along with sample processes, so you could get inspired how to write the process:
processes.area.
Area
Process calculating area of given polygon
processes.bboxinout.
Box
processes.buffer.
Buffer
processes.centroids.
Centroids
processes.feature_count.
FeatureCount
processes.grassbuffer.
GrassBuffer
processes.sayhello.
SayHello
processes.sleep.
Sleep
processes.ultimate_question.
UltimateQuestion