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20.4.1 Turtle, Pen and RawPen Objects

Most of the global functions available in the module are also available as methods of the `Turtle`, `Pen` and `RawPen` classes, affecting only the state of the given pen.

The only method which is more powerful as a method is `degrees()`, which takes an optional argument letting you specify the number of units corresponding to a full circle:

`degrees`( | [fullcircle])

  fullcircle is by default 360. This can cause the pen to have any angular units whatever: give fullcircle 2* for radians, or 400 for gradians.