That is the challenge, I am curious if it is even possible in Elixir. So unless someone finds a case that is truly beyond difficult or impossible, I may work on it little by little over time. 
Oh, and in that case with receive, I’d try to throw some error like (in the optimal case):
Function: Module.foo
Location: file.ex:76
Must return a type of: string
However it returns a type of: any()
Suggestion: Change or add a case from receive that adds a `when is_binary` condition
Or something like that. I want to be forced to put typing on anything and everything that is ambiguous, that is how you catch a lot of bugs.
