I forgot to mention, that I wonder if the interpreter shouldn't instead,
- either consider that since global a is used is g, it should be considered as also local to g from h point of view,
- or if h should be able to access f's version of a.
- (or if on the contrary, this ambiguity is the very reason to cause a syntax error, -- but in this case, one might need to change the text of the error message to make it more accurate. --)