code: def _init_alphabet_from_tokens(self, tokens):
          
          # Include all characters from all tokens in the alphabet to guarantee that
          # any token can be encoded. Additionally, include all escaping
          # characters.
          self._alphabet = {c for token in tokens for c in token}
          self._alphabet |= _ESCAPE_CHARS
docs: Initialize alphabet from an iterable of token or subtoken strings.