def _convert_key(self, key, is_setter=False):

        # allow arbitrary setting
        if is_setter:
            return list(key)

        for ax, i in zip(self.obj.axes, key):
            if ax.is_integer():
                if not is_integer(i):
                    raise ValueError("At based indexing on an integer index "
                                     "can only have integer indexers")
            else:
                if is_integer(i):
                    raise ValueError("At based indexing on an non-integer "
                                     "index can only have non-integer "
                                     "indexers")
        return key
Extract the short language code from its argument (or return the default
dataset/ETHPy150Open pydata/pandas/pandas/core/indexing.py/_AtIndexer._convert_key--crossover with--dataset/ETHPy150Open feincms/feincms/feincms/translations.py/short_language_code