anchor.diff:      : '=' type parameterName
       ;
   
  +//special rule for syntactic predicate
   specifiedFormalParameterStart
       : '=' declarationStart
       ;
  
positive.code:       )
      ;
  
  declarationStart
      : declarationKeyword 
      | type '...'? LIDENTIFIER
  
negative.code:     )
      ;
  
  //special rule for syntactic predicate
  //to distinguish between an annotation
  //and an expression statement
  annotatedDeclarationStart
      : declarationStart
      | LIDENTIFIER
  