def select_frame(self,locator):
self.do_command("<STR_LIT>", [locator,])<EOL>
Selects a frame within the current window.  (You may invoke this command
multiple times to select nested frames.)  To select the parent frame, use
"relative=parent" as a locator; to select the top frame, use "relative=top".
You can also select a frame by its 0-based index number; select the first frame with
"index=0", or the third frame with "index=2".


You may also use a DOM expression to identify the frame you want directly,
like this: ``dom=frames["main"].frames["subframe"]``


'locator' is an element locator identifying a frame or iframe