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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 label_durations(self, label_list_ids=None):
 """ Return a dictionary containing the total duration, every label-value in this corpus is occurring. Args: label_list_ids (list):
 If not None, only labels from label-lists with an id contained in this list are considered. Returns: dict: A dictionary containing the total duration with the label-value as key. """

        duration = collections.defaultdict(int)

        for utterance in self.utterances.values():
            for label_value, utt_count in utterance.label_total_duration(label_list_ids=label_list_ids).items():
                duration[label_value] += utt_count

        return duration