def addinivalue_line(self, name, line):
        x = self.getini(name)
        assert isinstance(x, list)
        x.append(line) # modifies the cached list inline
simple implementation of export: 
dataset/ETHPy150Open pytest-dev/pytest/_pytest/config.py/Config.addinivalue_line--crossover with--dataset/ETHPy150Open saga-project/BigJob/pilot/impl/pilotdata_manager.py/DataUnit.export