[xxyzz]

data/lemmas.json:

{
  "'neath": [  // lemma
    1,         // difficulty
    69182      // sense_id
  ],
  ...
}

You have to write some code to create your own data file(data/lemmas.json).

If you have some books have Word Wise enabled, you can use this script: https://github.com/xxyzz/WordDumb/bl.../add_lemmas.py.