'Set or return backgroundcolor of the TurtleScreen.
Arguments (if given): a color string or three numbers
in the range 0..colormode or a 3-tuple of such numbers.
Example (for a TurtleScreen instance named screen):
>>> screen.bgcolor("orange")
>>> screen.bgcolor()
\'orange\'
>>> screen.bgcolor(0.5,0,0.5)
>>> screen.bgcolor()
\'#800080\''

def bgcolor(self, *args):

    if args:
        color = self._colorstr(args)
    else:
        color = None
    color = self._bgcolor(color)
    if (color is not None):
        color = self._color(color)
    return color
