Incorrect examples

[MaximilianYan]

Repository has 10 code examples and unlike the other 8, "all.pr" & "simple.pr" crash when trying to run them.

It's not obvious that failing is caused by examples, so newcomer might be confused when testing his system on correctness.

Also an "arithmetic.pr" example does not contain if id == 0: line, so it is impossible to quickly check the correctness of its output.

[GassaFM]

Yeah, at this stage, perhaps the best action is to fix them so that they compile (preserving style etc. -- for example, all.pr shows different spacings, and that should be preserved).