anchor.diff:          typeParameters?
           typeConstraints?
           '(' annotation* type parameterName ')'
  -    ;
  +    ;*/
   
   interfaceDeclaration
       :
  
positive.code:     ;
  
  existenceEmptinessExpression
      : dateCompositionExpression ('exists' | 'nonempty')?
      ;
  
  //I wonder if it would it be cleaner to give 
  
negative.code: directive
      : 'return' assignable? 
      | 'produce' assignable
      | 'throw' expression 
      | 'break' 
      | 'found'
      ;
  