text: import { Mark } from 'tiptap'
  import { toggleMark } from 'tiptap-commands'
  
  export class Subscript extends Mark {
    get name() {
      return 'subscript'
    }
  
    get schema() {
      return {
        parseDOM: [
          {
            tag: 'sub',
          },
          {
            style: 'vertical-align',
            getAttrs: value => value === 'sub',
          },
        ],
        toDOM: () => ['sub', 0],
      }
    }
  
    commands({ type }) {
      return () => toggleMark(type)
    }
  
  }
  