anchor.diff:  part of polymorphic.api;
   
  -typedef void SubCommandHandler(List<String> args);
  +typedef SubCommandHandler(List<String> args);
   
   /**
    * A Command Event.
  
positive.code:     
      if (!handlers.keys.contains(cmd)) {
        usage();
        return;
      }
      
      handlers[cmd](cargs);
    }
  
    /**
  
negative.code:   /**
     * Handle Sub Commands
     */
    subcommands(Map<String, SubCommandHandler> handlers, {List<String> args}) {
      if (args == null) {
        args = this.args;
      }
      
      if (args.isEmpty) {
        usage();
        return null;
      }
      
      var cmd = args[0];
  