PyWPS-Demo comes along with sample processes, so you could get inspired how to write the process:
processes.area.Area
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