Usage examples? How can I use this library to build a unique word counter?

I don't see any examples from this repository so I don't know how to use it.

I want to build a unique word counter for a Russian text. So this lemmatizer should take as input: a text file, and output: number of unique lemmas. How can I build this?

https://russian.stackexchange.com/questions/25026/how-to-count-the-number-of-unique-words-lemmas-in-a-russian-text