 ==>   ^op_goal Proof   rpt strip_tac \\ rveq \\ fs []   \\ fs [flatSemTheory.do_app_def,list_case_eq,CaseEq "flatSem$v",PULL_EXISTS,          CaseEq "ast$lit",store_assign_def,option_case_eq]   \\ rw [] \\ fs [] \\ rveq \\ fs [LENGTH_EQ_NUM_compute] \\ rveq \\ fs []   \\ fs [] \\ rveq \\ fs [PULL_EXISTS,SWAP_REVERSE_SYM