class Session(object):
    """
    Session class
    """
    def __init__(self, revisions):
        # list of revisions
        self.revisions = revisions
        # session id
        self.session_id = self.revisions[0]
        # time of first revision
        self.start_time = self.revisions[0].time
        # time of last revision
        self.end_time = self.revisions[-1].time if len(self.revisions) > 1 else self.start_time
        # user
        self.user_id = self.revisions[0].user_id
