def add(self, instance, result):
    if self._check(result):
        for _feature in list(result.keys()):
            if (_feature not in list(self.csv.keys())):
                return ValueError
        self.content[instance] = result
        result = {key: [value] for (key, value) in result.items()}
        _df = pd.DataFrame.from_dict(result)
        self.csv = self.csv.append(_df, ignore_index=True)
def add(self, instance, result):
    if self._check(result):
        for _feature in list(result.keys()):
            if (_feature not in list(self.csv.keys())):
                return ValueError
        self.content[instance] = result
        result = {key: [value] for (key, value) in result.items()}
        _df = pd.DataFrame.from_dict(result)
        self.csv = self.csv.append(_df, ignore_index=True)