The Hilbert curve is a continuous fractal space filling curve first described by David Hilbert in 1891. This project can generate a seventh-order Hilbert curve. This project is an extension of http://scratch.mit.edu/projects/ngmr/59581 . INSTRUCTION: + Use the slider bar to change an order of the curve. + Click 'Start' to draw the curve. + When 'Overlay' selected, different curves are displayed simultaneously. + Click 'Clear' to reset the screen.