code: def align_add(tree, key, item, align_thres=2.0):
      
      for near_key, near_list in get_near_items(tree, key):
          if abs(key - near_key) < align_thres:
              near_list.append(item)
              return
      # Create a new group if no items are close
      tree[key] = [item]
docs: Adding the item object to a binary tree with the given
      key while allow for small key differences
      close_enough_func that checks if two keys are
      within threshold