Consider an alphabet with terminal symbols a, b). Write a context-free grammar in BNF (or EBNF) that will generate the set of all strings matching the pattern a2"b"a" (m21, n2 0) That is, your grammar must produce strings consisting of a non-zero even number of a's, followed by 0 or more b's, followed by half as many a's as in the original substring of a's. Examples are: You should also show, in as much detail as is necessary, that the grammar does what we want it to do (that is, argue for why your grammar generates all those strings, and only those)