another grammar example

examples2/grammar/contextFree2.txt

+CFG (
+{'S', 'B', 'C', 'D', 'E'},
+{'a', 'b'},
+{'S' -> 'D' 'S' | 'a' | 'C' 'D',
+'C' -> 'D' 'a' 'B' | 'b',
+'B' -> 'S' 'D' |,
+'D' -> 'B' 'E',
+'E' -> 'a' | 'C' 'D'
+},
+'D')