Sets the list element at index to element.
|key||string||key holding the list to set the element of.|
|index||number||index of the element to set.|
|element||string||value to set the element to.|
|Type||Resolves with||Rejected when|
|Promise<string>||On success, the promise resolves with OK.||If the list does not exist, or the index is out of bounds, the promise is rejected with an error.|