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():
            A = np.array([1., 2., 3.])
            A[0] = np.nan
            df = pd.DataFrame({'A': A})
            df.A.fillna(5.0, inplace=True)
            return df.A.sum()