document:
  nodes:
    - object: block
      type: paragraph
      nodes:
        - object: text
          leaves:
            - text: 'Hello '
              marks: []
            - text: Wo
              marks:
                - type: BOLD
            - text: rl
              marks:
                - type: BOLD
                - type: ITALIC
            - text: d
              marks:
                - type: BOLD
                - type: ITALIC
            - text: ' markup'
              marks:
                - type: ITALIC