code: def _split_into_words(sentences):
      full_text_words = []
      for s in sentences:
          if not isinstance(s, Sentence):
              raise (
                  ValueError(
                      "Object in collection must be of type Sentence"
                  )
              )
          full_text_words.extend(s.words)
      return full_text_words
  
file_path: sumy/sumy/evaluation/rouge.py
imports: from __future__ import absolute_import
  from __future__ import division, print_function, unicode_literals
  from ..models.dom import Sentence
label_desc: Use image node_id 2 for calling a global function with example usage: _split_into_words(sentences) and returns: full_text_words