p |int |magic_clearenv |NN SV* sv|NN MAGIC* mg
p |int |magic_clear_all_env|NN SV* sv|NN MAGIC* mg
dp |int |magic_clearhint|NN SV* sv|NN MAGIC* mg
-p |int |magic_clearisa |NN SV* sv|NN MAGIC* mg
+p |int |magic_clearisa |NULLOK SV* sv|NN MAGIC* mg
p |int |magic_clearpack|NN SV* sv|NN MAGIC* mg
p |int |magic_clearsig |NN SV* sv|NN MAGIC* mg
p |int |magic_existspack|NN SV* sv|NN const MAGIC* mg