How to use the slate-hotkeys.isMoveLineBackward function in slate-hotkeys

if (Hotkeys.isDeleteWordForward(event)) {
      return editor.deleteWordForward()
    }

    if (Hotkeys.isRedo(event)) {
      return editor.redo()
    }

    if (Hotkeys.isUndo(event)) {
      return editor.undo()
    }

    // COMPAT: Certain browsers don't handle the selection updates properly. In
    // Chrome, the selection isn't properly extended. And in Firefox, the
    // selection isn't properly collapsed. (2017/10/17)
    if (Hotkeys.isMoveLineBackward(event)) {
      event.preventDefault()
      return editor.moveToStartOfBlock()
    }

    if (Hotkeys.isMoveLineForward(event)) {
      event.preventDefault()
      return editor.moveToEndOfBlock()
    }

    if (Hotkeys.isExtendLineBackward(event)) {
      event.preventDefault()
      return editor.moveFocusToStartOfBlock()
    }

    if (Hotkeys.isExtendLineForward(event)) {
      event.preventDefault()