docs: def main():
      """
      generates a random world, sets terrain and runs agents in it
       TODO - need to change pieces in multiple places (see worlds.py, cls_grid, world_generator)
       (takes about 5 minutes to make 500x400 grid with 8% blockages)
      """
      width       =  20   # grid width 
      height      =  10   # grid height
      iterations  =  20   # how many simulations to run
      num_agents  =   6   # number of agents to enter the world
      
      w = build_world(height, width)
      print(w)
      a = create_random_agents(w, num_agents)
      sim = my_world.WorldSimulation(w, a, 1)
      sim.run(iterations, 'Y', log_folder + os.sep + 'agt_run')
      sim.world.grd.save('test_world_traversed.txt')