'Set turtle-mode (\'standard\', \'logo\' or \'world\') and perform reset.
Optional argument:
mode -- one of the strings \'standard\', \'logo\' or \'world\'
Mode \'standard\' is compatible with turtle.py.
Mode \'logo\' is compatible with most Logo-Turtle-Graphics.
Mode \'world\' uses userdefined \'worldcoordinates\'. *Attention*: in
this mode angles appear distorted if x/y unit-ratio doesn\'t equal 1.
If mode is not given, return the current mode.
Mode      Initial turtle heading     positive angles
\'standard\'    to the right (east)       counterclockwise
\'logo\'        upward    (north)         clockwise
Examples:
>>> mode(\'logo\')   # resets turtle heading to north
>>> mode()
\'logo\''

def mode(self, mode=None):

    if (mode is None):
        return self._mode
    mode = mode.lower()
    if (mode not in ['standard', 'logo', 'world']):
        raise TurtleGraphicsError(('No    turtle-graphics-mode    %s' % mode))
    self._mode = mode
    if (mode in ['standard', 'logo']):
        self._setscrollregion(((- self.canvwidth) // 2), ((- self.canvheight) // 2), (self.canvwidth // 2), (self.canvheight // 2))
        self.xscale = self.yscale = 1.0
    self.reset()
