How does Couchdb calculates the document revision number?

Whats the exact algorithm to calculate the CouchDB revision number. CouchDB uses a deterministic algorithm to calculate the document revision number. Here is one relevant doc I found: https://stackoverflow.com/questions/5954864/how-does-couchdb-calculate-the-revision-number Buts its all in elrang, I am trying to implement it in dart. I use sample document : {"_id":"123-this-is-an-id","hello":"world","testing":123} for testing. When I do the MD5 hash of it , its gives me : f0853833850bce08dce0896e010a375e, where as the couchdb revision number is : "_rev": "1-43dce8fe7e9a26b49390e3727a015cc0" I google it everywhere, but if I can find the algorithm some where in text , UI can convert it into dart.