(what movies were made in 1955)
(what movie was made in 1964)
Instead of creating two different
pattern/action pairs for these, we can
match both of them with the pattern:
(what (movie movies) (was were) made in _)
"_" is a wild-card which:
A list (item1 ... itemn) in a pattern matches the corresponding word in the query if the word is one of the items in the list. Call the list an option list.