def _get_cache(self):

        cache = []
        if self.pos2:
            for row in range(self.pos1[0], self.pos2[0]+1):
                for col in range(self.pos1[1], self.pos2[1]+1):
                    cache.append(self.sheet.cell(row=row, column=col).value)
        else:
            cell = self.sheet.cell(row=self.pos1[0], column=self.pos1[1])
            cache.append(cell.value)
        return cache
Exceptions raised in `create_proxy_to` operations are reported as
dataset/ETHPy150Open cloudera/hue/desktop/core/ext-py/tablib-0.10.0/tablib/packages/openpyxl/chart.py/Reference._get_cache--crossover with--dataset/ETHPy150Open ClusterHQ/flocker/flocker/node/test/test_container.py/SetProxiesTests.test_create_proxy_errors_as_errbacks