I would be happy to write a PR that implements that.However, i am not sure which way is better to construct a list from the returnvalue (an iterable, hopefully) of keys() etc.:- Call PyList_Type() (in each of PyMapping_Keys() etc.) on the iterable, and  overwrite the error message in case it is a TypeError.- Write a helper function iterable_as_list(), which uses PyObject_GetIter() and  PySequence_List(), and call it in each of PyMapping_Keys() etc..  (iterable_as_list() would receive "keys" etc., so that it would raise the  appropriate error message, in case of a TypeError.)ISTM that the first one is simpler, but I am not sure about the performancedifference between them.