-* explicit check that stdout and $3 are not written simultaneously
-* explicit check (similar to apenwarr/redo's one) that generated target
- was not modified "externally" outside the redo, preventing its
- overwriting, but continuing the build
+* explicit useful and convenient checks from apenwarr/redo:
+ * check that $1 was not touched during .do execution
+ * check that stdout and $3 are not written simultaneously
+ * check that generated target was not modified "externally" outside
+ the redo, preventing its overwriting, but continuing the build