Valid functions (methods?) for changing clef via plugin?

This was asked previously by another member in https://musescore.org/en/node/121891, but I hadn't seen any responses.
Trying to write a simple script to change the clef type (to bass clef, aka "F" clef, in this case), but not having success...

var BC= newElement(Element.CLEF);
BC.clefType("F"); // here I also tried BC.setClef("F") and BC.setClefType("F")
cursor.add(BC);

Any help would be appreciated...thanks!