For each director, return the director's name together with the title of the movie they directed that received the highest rating among all of their movies, and the value of that rating. Ignore movies whose director is NULL.
return directors ;return #1 besides  NULL ;return movies of   #2 ;return ratings of   #3 ;return the  highest of   #4 for each #1 ;return #3 where #4 is equal to #5 ;return names of   #1 ;return titles of   #6 ;return #7 ,  #8 ,   #5
['select', 'discard', 'project', 'project', 'group', 'comparative', 'project', 'project', 'union']