def METHOD_NAME(self, impression):
    """
    Examine an impression to determine and set it's previous time accordingly.
    :param impression: Impression to track
    :type impression: splitio.models.impressions.Impression
    :returns: Impression with populated previous time
    :rtype: splitio.models.impressions.Impression
    """
    previous_time = self._cache.METHOD_NAME(self._hasher.process(impression), impression.time)
    return Impression(impression.matching_key,
                      impression.feature_name,
                      impression.treatment,
                      impression.label,
                      impression.change_number,
                      impression.bucketing_key,
                      impression.time,
                      previous_time)