Racket submodule example

sub

#lang racket
  
(module foo racket
  (module bar typed/racket ;;submodules can leverage different languages
    (provide baz three)
    
    (define: three : Number 3)
    (define (baz) '(foo bar baz))
    (define (bit) '(this is private))))

(require (submod 'foo bar))

(baz)
three