code: def make_niche_grid(res_dict, world_size=(60, 60)):
      
  
      # Initialize array to represent world
      world = initialize_grid(world_size, set())
  
      # Fill in data on niches present in each cell of the world
      for res in res_dict:
          for cell in res_dict[res]:
              world[cell[1]][cell[0]].add(res)
  
      return world
docs: Converts dictionary specifying where resources are to nested lists
      specifying what sets of resources are where.
  
      res_dict - a dictionary in which keys are resources in the environment
      and values are list of tuples representing the cells they're in.
  
      world_size - a tuple indicating the dimensions of the world.
             Default = 60x60, because that's the default Avida world size
  
      Returns a list of lists of sets indicating the set of resources
      available at each x,y location in the Avida grid.