class_docstr: Encodes/decodes between strings and integer representations.
class_docstr_tok: ["Encodes\/decodes","between","strings","and","integer","representations","."]
code: def __init__(self, chars: str, max_len_query_digit: int = 3) -> None:
      self._chars = sorted(set(chars))
      self._char_indices = {
          ch: idx + 2 for idx, ch in enumerate(self._chars)
      }
      self._indices_char = {
          idx + 2: ch for idx, ch in enumerate(self._chars)
      }
      self._indices_char[self.pad_id] = "_"
      # Maximum length of a single input digit.
      self._max_len_query_digit = max_len_query_digit
  
imports: import random
  from typing import Any, Dict, Generator, Optional, Tuple
  import jax.numpy
  import numpy
label_desc: Use image node_id 1 to create a new CharacterTable object  with example: obj = CharacterTable(chars, max_len_query_digit)