anchor.diff:      ;
   
   struct
  -    : STRUCT IDENTIFIER LCURLY field* RCURLY type_annotations? -> ^(STRUCT IDENTIFIER field* type_annotations?)
  +    : STRUCT IDENTIFIER LCURLY field* RCURLY type_annotations? list_separator? -> ^(STRUCT IDENTIFIER field* type_annotations?)
       ;
   
   union
  
positive.code:     ;
  
  enum_rule
      : ENUM IDENTIFIER LCURLY enum_field* RCURLY -> ^(ENUM IDENTIFIER enum_field*)
      ;
  
  enum_field
  
negative.code:     ;
  
  service
      : SERVICE s=IDENTIFIER (EXTENDS e=IDENTIFIER)? LCURLY f=function* RCURLY type_annotations? list_separator? -> ^(SERVICE $s ^(EXTENDS_ $e?) function* type_annotations?)
      ;
  
  
  