anchor.diff:      rule typevar_item_or_var:
           VAR [ typevar_param_list ]
           | typevar_item
  -        | TOKACTION
  -        | TOKACTIONVALUE
   
       rule Type_list:
           ( type_decl
  
positive.code:         |    (TOKTAGGED term_single)+ [term_single]
          |    BUILTINVAR [ param_list ]
          |    term_single
          |    builtin_type
          |    STR {{ return STR }}
          |    paren_expression
          |    LBRACE assign_rvalue ( COMMA assign_rvalue )* RBRACE
  
negative.code:             )
          )+
  
      rule interface_declaration:
          TOKINTERFACE CLASSVAR*
          #typevar_item_or_var [ VAR ]
          (typevar_item | VAR) [ VAR ]
              ( equal_value
              | [ SEMICOLON ] [ interface_body ] TOKENDINTERFACE [ COLON VAR ]
              )
  
      rule function_declaration:
          TOKFUNCTION [ Type_list ]
  