-- b) Modify that function so that it only returns the combinations that begin
-- with a p.
combos2 = [(a,b,c)
          | a <- stops,
            b <- vowels,
            c <- stops,
            a == 'p']
combos2 = [(a,b,c)
          | a <- stops,
            b <- vowels,
            c <- stops,
            a == 'p']
combos2 = [(a,b,c)
          | a <- stops,
            b <- vowels,
            c <- stops,
            a == 'p']