A real Logo-style command interpreter — forward/turn/pen/repeat — drawn live on Canvas2D.
Low = draws command-by-command slowly. High = near-instant.
forward N / fd N — move & draw
back N / bk N — move backward
turn N / right N / rt N — rotate clockwise
left N / lt N — rotate counter-clockwise
penup / pu, pendown / pd
push / pop — save/restore state (branches)
home — reset to center
color #hex — change stroke color
repeat N [ ... ] — real loop, nestable