document:
  nodes:
    - object: block
      type: ol_list
      nodes:
        - object: block
          type: list_item
          nodes:
            - object: block
              type: paragraph
              nodes:
                - object: text
                  leaves:
                    - text: Item 1
            - object: block
              type: ol_list
              nodes:
                - object: block
                  type: list_item
                  nodes:
                    - object: block
                      type: paragraph
                      nodes:
                        - object: text
                          key: '_selection_key'
                          # split here "It|em 1.1"
                          leaves:
                            - text: Item 1.1
                    - object: block
                      type: ol_list
                      nodes:
                        - object: block
                          type: list_item
                          nodes:
                            - object: block
                              type: paragraph
                              nodes:
                                - object: text
                                  leaves:
                                    - text: Item 1.1.1
                        - object: block
                          type: list_item
                          nodes:
                            - object: block
                              type: paragraph
                              nodes:
                                - object: text
                                  leaves:
                                    - text: Item 1.1.2