anchor.diff:  
   satisfiesCondition
       : 'satisfies' type type
  +    -> ^(SATISFIES_EXPR type type)
       ;
   
   controlStructure
  
positive.code:     EXISTS_EXPR;
      NONEMPTY_EXPR;
      IS_EXPR;
      SPECIAL_ARG;
      //PRIMARY;
  }
  
negative.code:     METATYPE_LIST;
      NAMED_ARG;
      SEQ_ARG;
      RET_STMT;
      BLOCK;
      THROW_STMT;
  