class_docstr: Abstract parser of input format into DOM.
code: def tokenize_words(self, sentence):
      return self._tokenizer.to_words(sentence)
  
imports: from __future__ import absolute_import
  from __future__ import division, print_function, unicode_literals
label_desc: Use image node_id 3 for calling the DocumentParser obj's underlying member method code with example usage: obj.tokenize_words(sentence) and returns: self