readme: This is a BPE tokenizer based on "Salesforce/codegen-350M-mono".  
  The tokenizer has been trained to treat spaces like parts of the tokens (a bit like sentencepiece)
  so a word will be encoded differently whether it is at the beginning of the sentence (without space) or not. 
  
  We used ArXiv subset of The Pile dataset and proof steps from [lean-step-public](https://github.com/jesse-michael-han/lean-step-public) datasets to train the tokenizer.
  