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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _build_word_co_occurance_graph(self, phrase_list):
 """Builds the co-occurance graph of words in the given body of text to compute degree of each word. :param phrase_list: List of List of strings where each sublist is a collection of words which form a contender phrase. """

        co_occurance_graph = defaultdict(lambda: defaultdict(lambda: 0))
        for phrase in phrase_list:
            # For each phrase in the phrase list, count co-occurances of the
            # word with other words in the phrase.
            #
            # Note: Keep the co-occurances graph as is, to help facilitate its
            # use in other creative ways if required later.
            for (word, coword) in product(phrase, phrase):
                co_occurance_graph[word][coword] += 1
        self.degree = defaultdict(lambda: 0)
        for key in co_occurance_graph:
            self.degree[key] = sum(co_occurance_graph[key].values())