Draws a line (a direct path between two points) to the screen.
:x1 - The x-coordinate of the first point (number)
:y1 - The y-coordinate of the first point (number)
:x2 - The x-coordinate of the second point (number)
:y2 - The y-coordinate of the second point (number)
[:line {:x1 0, :y1 0, :x2 50, :y2 50}]