class_docstr: Vocabulary containing character-level information.
class_docstr_tok: ["Vocabulary","containing","character-level","information","."]
code: def encode_chars(self, sentence):
      chars_ids = [
          self.word_to_char_ids(cur_word)
          for cur_word in sentence.split()
      ]
      return np.vstack([self.bos_chars] + chars_ids + [self.eos_chars])
  
imports: import random
  import numpy
  from textattack.shared.utils import LazyLoader
label_desc: Use image node_id 6 for calling the CharsVocabulary obj's underlying member method code with example usage: obj.encode_chars(sentence) and returns: np