.. function:: screensize(canvwidth=None, canvheight=None, bg=None)
- :param canvwidth: positive integer, new width of canvas in pixels
- :param canvheight: positive integer, new height of canvas in pixels
- :param bg: colorstring or color-tupel, new background color
+ :param canvwidth: positive integer, new width of canvas in pixels :param
+ canvheight: positive integer, new height of canvas in pixels :param 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