motivation: design and implement an simple extractor to bridge Python developer and knowledge of PyClowder library. It is inevitable for us to assume a learning curve for Python developer to be familiar with PyClowder api library and start to code extractor.

Simple extractor will provide a way to decouple the function body of metadata computation from the full implementation of extractor.  Developers will just focus on their own extract function body. Meanwhile, simple extractor will take developer defined function as input to do extraction and then parse and organize the metadata output into Clowder defined metadata data-struct and submit back to Clowder.

https://opensource.ncsa.illinois.edu/confluence/display/CATS/Simple+Extractor+wrapper+for+basic+functions