'Return the list of available tab names.  If no tab names
are available, wait for them to load.  Raises a `BrokenPromiseError`
if the tab names fail to load.'

@property
def tab_names(self):

    def _check_func():
        tab_names = self.q(css='ol.course-tabs    li    a').text
        return ((len(tab_names) > 0), tab_names)
    return Promise(_check_func, 'Get    all    tab    names').fulfill()
