I've added three lines to cls.code to test_hyperparser. So I can test for subscripts with double quotes, single quotes and with no strings at all.

Should I implement try_open_completions_event for COMPLETE_DICTIONARY? Calling this event everytime someone types a string seemed a bit expensive in my opinion.

I'm attaching the new patch.

As fas as the signed contributor, I've already signed last week but still waiting.