def extract_keywords_from_sentences(self, sentences):
        """Method to extract keywords from the list of sentences provided.

        :param sentences: Text to extraxt keywords from, provided as a list
                          of strings, where each string is a sentence.
        """
        phrase_list = self._generate_phrases(sentences)
        self._build_frequency_dist(phrase_list)
        self._build_word_co_occurance_graph(phrase_list)
        self._build_ranklist(phrase_list)