const decreaseBlockDepth = (block, editorState) => {
  const blockKey = block.getKey();
  const depth = block.getDepth();
  const newBlock = block.set('depth', depth - 1);
  const contentState = editorState.getCurrentContent();
  const blockMap = contentState.getBlockMap();
  const newBlockMap = blockMap.set(blockKey, newBlock);
  return EditorState.push(
    editorState,
    contentState.merge({ blockMap: newBlockMap }),
    'adjust-depth'
   );
}