>>> import soy
>>> b = soy.bodies._bodies.Body
>>> s = soy.shapes.Shape
>>> s.body
<attribute 'body' of 'soy.shapes.Shape' objects>
>>> s.body = b
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
TypeError: can't set attributes of built-in/extension type 'soy.shapes.Shape'