SpaCy "Doc"
https://github.com/explosion/spaCy/blob/75d2a05c2938f412f0fae44748374e4de19cc2be/spacy/tokens/doc.pyx#L80

SpaCy "Vocab"
https://github.com/explosion/spaCy/blob/75d2a05c2938f412f0fae44748374e4de19cc2be/spacy/vocab.pyx#L25

SpaCy "Token"
https://github.com/explosion/spaCy/blob/75d2a05c2938f412f0fae44748374e4de19cc2be/spacy/tokens/token.pyx#L27
