Tutorial about how to wriite a segmentation Editor Effects plugin

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Hi there!
Currently I want to implement a seg. algorithm with the help of Slicer Segementation Editor. My question is is there any guide/tutorials to begin? I have already downloaded the plugins such as Nvidia AIAA etc. and went through their python code in Slicer-build\NA-MIC\Extensions-29738\ subfolders. But I am stiil not so clear of the development protocal. Thanks.