anchor.diff:      | tryStatement
       | debuggerStatement
       | functionDeclaration
  -    | classDeclaration
       ;
   
   block
  
positive.code:     : block
      | variableStatement
      | emptyStatement
      | expressionStatement
      | ifStatement
      | iterationStatement
  
negative.code:     | EOF
      | {this.lineTerminatorAhead()}?
      | {this.closeBrace()}?
      ;
  