@property
    def previous_page_number(self):
        if not self.has_previous:
            return False
        return self.number - 1
Calculates Dice's coefficient ... (2*number of common terms)/(number of terms in x +
dataset/ETHPy150Open tonioo/modoboa/modoboa/lib/paginator.py/Page.previous_page_number--crossover with--dataset/ETHPy150Open radlab/sparrow/src/main/python/third_party/stats.py/dices