BrianHung

/**
* Given two commands (commandA and commandB), returns a new command that when applied 
* to a ProseMirror state that uses the prosemirror-history plugin applies commandA and 
* then commandB so that both commands are undone with a single undo action. 
**/
const combineCommands =
  (commandA: Command, commandB: Command) =>
  (state: EditorState, dispatch?: (tr: Transaction) => void): boolean => {
    return commandA(state, (transactionA: Transaction) => {
      const { state: stateA } = state.applyTransaction(transactionA)