Multidocument files with mixed exec-mode

[kyleect]

(exec-mode 'module)

(export sum)
(define sum (lambda (a b) (+ a b)))

(sum 5 5) ;; Errors! Modules can only have defines, imports and exports
---
(exec-mode 'test)

(test "adds two numbers together" (lambda ()
  (assert (sum 5 5) 10)))

(test "should error is missing arguments" (lambda ()
  (assert-throws (sum) "Required 2 arguments but got 0")))
---
(exec-mode 'script)

(define a 10)
(define b 30)

(display (string-append "When you add " a " and " b " you get " (sum a b)))