class_docstr: Encodes each byte to an id. For 8-bit strings only.
code: def vocab_size(self):
      return 2**8 + self._num_reserved_ids
  
imports: import re
  import six
label_desc: Use image node_id 4 for calling the ByteTextEncoder obj's underlying member method code with example usage: obj.vocab_size() and returns: unknown