💡 How to use. Draw your graph with your mouse/finger/stylus. To add a vertex, draw a circle. Vertices will
be shown in yellow while edges are in blue. In order to erase a portion of your drawing, just scribble on it
till the scribble (and the underlying portion) turns grey. To cancel/redo, use Ctrl+Z/Cmd+Z and Ctrl+Y/Cmd+Y.