Picture Object
Each backend provides an object named Picture that provides easy access to constructors. A constructor is any method on an algebra methods that produces a Drawing[A] but doesn't have any Drawing[A] input parameters. For example, all the methods on the Shape algebra are constructors because they produce a Drawing[Unit] but none of them take a Drawing as an input.
The Picture object allows us to write
Picture.circle(100)to call the circle method on Shape.
Be aware that calling Picture.circle will create a Picture. Calling the Shape algebra directly produces a Drawing, which is usually not what we want, so Doodle adds this convenience for the API it expects you to use.