Support parsing statements or definitions within a function body.

[Ed94]

We can still ignore everything past an assignment expression ( everything past the <assignment token> ).

Nested assignments ( <identifier> <assign op> <identifier <assign op> <expression>; ) will be a pain.
If encountered were going to translate into two statements with a duplicated expression instead. Otherwise I would have support an undetermined amount of names...

This is a similar situation to multiple variable declarations under one type scope (Which we'll be doing the same thing to in the future).

Statement asts could be just a version of untyped as execution ast's are currently.
We would need to support parsing lambdas. ( Unreal is riddled with them... )

Parsing variables is already supported. We would need to support the thread_local as a specifier ( just verify what's already in the implementation works... )