@NotNull
  ThreeState compareAST(@NotNull ASTNode oldNode,
                        @NotNull LighterASTNode newNode,
                        @NotNull FlyweightCapableTreeStructure<LighterASTNode> structure);
@NotNull
  ThreeState compareAST(@NotNull ASTNode oldNode,
                        @NotNull LighterASTNode newNode,
                        @NotNull FlyweightCapableTreeStructure<LighterASTNode> structure)