docs: def insert(self, key, value):
          """Insert a key-value pair in the list.
  
          The pair is inserted at the correct location so that the list remains
          sorted on *key*. If a pair with the same key is already in the list,
          then the pair is appended after all other pairs with that key.
          """
          self._find_lte(key)
          node = self._create_node(key, value)
          self._insert(node)