@Nullable
  default <T extends PyAstElement> T childToPsi(IElementType elType) {
    final ASTNode node = getNode().findChildByType(elType);
    if (node == null) {
      return null;
    }

    //noinspection unchecked
    return (T)node.getPsi();
  }
@Nullable
  default <T extends PyAstElement> T childToPsi(IElementType elType)