+ (components '())
+ (key #f))
+ (receive (e c k) (new-entity (list (make-a 1 2) (make-b)) entities components)
+ (set! entities e)
+ (set! components c)
+ (set! key k)
+ (display k) (newline))
+ (format #t "New entity with a and b:~%~a~%~a~%~%" entities components)
+
+ (receive (e c k) (new-entity (list (make-a 10 20)) entities components)
+ (set! entities e)
+ (set! components c)
+ (display k) (newline))
+ (format #t "New entity with a:~%~a~%~a~%~%" entities components)
+
+ (receive (e c) (set-entity-components key `((b . #f) ,(make-a 50 50)) entities components)
+ (set! entities e)
+ (set! components c))
+ (format #t "First entity removes b and changes a:~%~a~%~a~%~%" entities components)
+
+ (receive (e c) (remove-entity key entities components)
+ (set! entities e)
+ (set! components c))
+ (format #t "Removes first entity:~%~a~%~a~%~%" entities components)
+
+ (receive (e c k) (new-entity (list (make-a 1 2) (make-b)) entities components)