Goal:

A shark chases a goldfish until the shark is near (within .5 meters)
the goldfish.

The goldfish escapes by moving in random direction and distance.

The shark swims faster than the goldfish.


Storybook:

1.  World.myFirstMethod (main story)

      while Shark is more than .5 meters away from Goldfish
        Goldfish escapes
        Shark chases
      Shark eats goldfish...


2.  Goldfish.escape method

      Goldfish moves away (more realistic: in random direction and distance in 3D) 
      Goldfish moves its tail


3.  Shark.chase method

      Shark moves toward the goldfish
      Shark moves its tail