public static @Nullable ASTNode findSibling(ASTNode start, IElementType elementType) {
    ASTNode child = start;
    while (true) {
      if (child == null) return null;
      if (child.getElementType() == elementType) return child;
      child = child.getTreeNext();
    }
  }
public static @Nullable ASTNode findSibling(ASTNode start, IElementType elementType)