First note that you are using a very old documentation of the demo (v 1.3.0). The newest version can be found here: Auto adaptive Poisson equation — DOLFIN documentation
Please also format your code such that it is readable, i.e. using 3x` encapsulation.
Also note that you need to produce a minimal code example, this implies that the code should be executable on any system using fenics, without having to add extra code. See Read before posting: How do I get my question answered? - #4 by nate for examples of how minimal code examples should look like.