turtle.screensize(canvwidth=None, canvheight=None, bg=None)
Parameters:
canvwidth – positive integer, new width of canvas in pixels
canvheight – positive integer, new height of canvas in pixels
bg – colorstring or color-tuple, new background color
If no arguments are given, return current (canvaswidth, canvasheight). Else resize the canvas the turtles are drawing on. Do not alter the drawing window. To observe hidden parts of the canvas, use the scrollbars. With this method, one can m