def popitem(self):
        'Remove and return an item pair from maps[0]. Raise KeyError is maps[0] is empty.'
        try:
            return self.maps[0].popitem()
        except __HOLE__:
            raise KeyError('No keys found in the first mapping.')
dataset/ETHPy150Open ionelmc/python-aspectlib/src/aspectlib/py2chainmap.py/ChainMap.popitem