anchor.diff:  
   attr_constant_name
       :   NAME_NAME ATTR_EQ ATTR_VALUE_START t=NAME ATTR_VALUE_END
  -        -> CONSTANTNAME[$t, ($t.text)->chars];
  +        -> CONSTANTNAME[$t, ($t.text)->chars]
  +    ;
   
   attr_expression_value
       :   NAME_VALUE! ATTR_EQ! ATTR_VALUE_START! expression ATTR_VALUE_END!
  
positive.code:     	doc=SHORTDOC*
          enum_option+
          TAG_END_BITFLAGS SHORTDOC*
          -> ^(ENUMDEF ^(DOC $doc) $name $type enum_option+);
  
  struct_add
  @init {
  
negative.code: not_test
  	:   OP_LOGICAL_NOT^ not_test
  	|   comparison
  	;
  
  comparison
  