skimage.graph module

Hi, Can anyone help me understand what is skimage.graph module is intended for ? the API Reference page<http://scikit-image.org/docs/dev/api/skimage.graph.html> for graph module does not include any description about the module. just a single line about the module would suffice like done in sklearn documentation<http://scikit-learn.org/stable/modules/classes.html#module-sklearn.cluster> . Currently the module has Minimum Cost Path algorithms and Shortest Path. What I'm trying to figure out is why they are being kept in a separate module, as in what general context are they useful. Thanks, Regards, Siva Prasad Varma.