This means the second item in the AST is no longer an integer
(representing the line), but a keywords list. Code that relies
on the line information from AST or that manually generate AST
nodes need to be properly updated.
The following code:
counter = 1
counter = 2
Is now rewritten internally to:
counter = 1
counter@1 = 2
Which gives us a couple things:
1. Better debugging
2. We can now show warnings for rebound variables not used
Elixir also keeps `_@` prefix to store internal variables
(for example, `_@1`, `_@MODULE`, etc).
Closes#607.
José Valim