def connect(self): 
        try:
            self.connection = pymongo.Connection(self.host, self.port)
            self.db = self.connection[self.name]
        except AutoReconnect:
            raise DatabaseException("It's not possible connect to the database")
def test_impl(n):
            df = pd.DataFrame({'A': np.ones(n), 'B': np.random.ranf(n)})
            df.A.fillna(5.0, inplace=True)
            DF = df.A.fillna(5.0)
            s = DF.sum()
            m = df.A.mean()
            v = df.A.var()
            t = df.A.std()
            Ac = df.A.cumsum()
            return Ac.sum() + s + m + v + t