def assign_id(self,locator,identifier):
self.do_command("<STR_LIT>", [locator,identifier,])<EOL>
Temporarily sets the "id" attribute of the specified element, so you can locate it in the future
using its ID rather than a slow/complicated XPath.  This ID will disappear once the page is
reloaded.

'locator' is an element locator pointing to an element
'identifier' is a string to be used as the ID of the specified element