Turtle Art is an activity with a Logo-inspired graphical "turtle"
that draws colorful art based on Scratch-like snap-together visual
programming elements.
There are many restrictions compared to LOGO. The two allowed user-defined
procedures can't have parameters. Only two numeric global variables
are available, no lists or other data-structures. You can't make user defined
functions which return a value. The conditionals and some of the functions
only take constants or variables, not expressions. Limited screen real-estate
makes building large programs unfeasible.