Checks this period conflicts with another period.

def conflicts_with(self, period):
        "Checks this period conflicts with another period."
        if self.tba or period.tba:
            return False
        same_day = False
        for i in self.int_days:
            if i in period.int_days:
                same_day = True

        if not same_day:
            return False

        return self.start <= period.start <= self.end or \
            period.start <= self.start <= period.end or \
            self.start <= period.end <= self.end or \
            period.start <= self.end <= period.end