code: def highlight_cell_surroundings(self, target_y, target_x):
          
          #print('SELF_WORLD', self.world)
          #print('target_y, target_x, self.world.grd.grid_height, self.world.grd.grid_width ', target_y, target_x, self.#world.grd.grid_height, self.world.grd.grid_width )
          #exit(0)
          
          if target_y < 1:
              print("target too close to top")
          if target_y > self.world.grd.grid_height - 1:  
              print("target too close to bottom")
          if target_x < 1:
              print("target too close to left")
          if target_x < self.world.grd.grid_width:  
              print("target too close to right")
          #valid_cells = ['\\', '-', '|', '/']    
          self.world.grd.set_tile(target_y - 1, target_x - 1, '\\')
          self.world.grd.set_tile(target_y - 0, target_x - 1, '-')
          self.world.grd.set_tile(target_y + 1, target_x - 1, '/')
  
          self.world.grd.set_tile(target_y - 1, target_x - 0, '|')
          self.world.grd.set_tile(target_y + 1, target_x - 0, '|')
          
          self.world.grd.set_tile(target_y - 1, target_x + 1, '/')
          self.world.grd.set_tile(target_y - 0, target_x + 1, '-')
          self.world.grd.set_tile(target_y + 1, target_x + 1, '\\')
docs: highlights the cells around a target to make it simpler
          to see on a grid. Currently assumes the target is within
          the boundary by 1 on all sides