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