anchor.diff:   | throwStatement
    | tryStatement
    | debuggerStatement
  - | importStatement
  - | exportStatement
  - | lexicalStatement
  - ;
  -
  -lexicalStatement
  -  : 'let' bindingList
  -  | 'const' bindingList
  +;
  +
  +lexicalDeclaration
  +  : Let bindingList
  +  | Const bindingList
   ;
   
   bindingList
  
positive.code:   | Identifier 'as' Identifier
  ;
  
  exportStatement
    : 'export' '*' fromClause ';'?
    | 'export' namedImports fromClause? ';'?
    | 'export' variableStatement
    | 'export' functionDeclaration
    | 'export' lexicalStatement
    | 'export' 'default' functionDeclaration
    | 'export' 'default' singleExpression ';'?
  ;
  
  /// Block :
  
negative.code: sourceElement
   : statement
   | functionDeclaration
   | importDeclaration
   | exportDeclaration
   | lexicalDeclaration
   | classDeclaration
   ;
  
  /// Statement :
  