def getall(self):
        try:
            spec = {'data': {'$exists': 1}}
            fields = {'_id': 0}
            sort = [('tid', 1)]
            cur = self.db.docs.find(spec, fields, sort=sort)
        except Exception as e:
            raise DatabaseException(e)
        return [Document(**row) for row in cur]
def dec_r(self, ind):
        r, c = self.row_col(ind)
        r -= 1
        if r < 0:
            r = self.nr - 1
        if r == (self.nr - 1) and c == (self.nc - 1):
            r = self.nr - 2
        return self.indx(r, c)