anchor.diff:    UnitGenerator(this.uri, this.unit, this.directory, this.libName, this.infoMap,
         this.rules);
   
  -  AstNode visitConversion(Conversion node) {
  +  void visitConversion(Conversion node) {
       out.write('/* Unimplemented: ');
       out.write('${node.description}');
       out.write(' */ ');
       node.expression.accept(this);
  -    return node;
     }
   
     String get outputPath {
  
positive.code:       out.write('.');
        node.identifier.accept(this);
      }
      return node;
    }
  
    AstNode visitIntegerLiteral(IntegerLiteral node) {
      out.write('${node.value}');
      return node;
    }
  
    AstNode visitStringLiteral(StringLiteral node) {
      out.write('"${node.stringValue}"');
      return node;
    }
  
    AstNode visitBooleanLiteral(BooleanLiteral node) {
      out.write('${node.value}');
      return node;
    }
  
    AstNode visitDirective(Directive node) {
      return node;
    }
  
    AstNode visitNode(AstNode node) {
      out.write('/* Unimplemented ${node.runtimeType}: $node */');
      return node;
    }
  
    static const Map<String, String> _builtins = const <String, String>{
  
negative.code:       node.expression.accept(this);
        out.write(';\n');
      }
    }
  
    void _generateVariableList(VariableDeclarationList list, bool lazy) {
  