anchor.diff:    }
     return null;
   }
  -
  -o.Expression _extractFunction(o.Expression returnExpr) {
  -  final callExpr = returnExpr as o.InvokeMethodExpr;
  -  return o.ReadPropExpr(callExpr.receiver, callExpr.name);
  -}
  
positive.code:       numArgs = 1;
      }
  
      final wrapperName = 'eventHandler$numArgs';
      return o.InvokeMemberMethodExpr(wrapperName, [handlerExpr]);
    }
  
    bool _isTearOff(BoundEventAst hostEvent) =>
  
negative.code:   o.Expression _simpleHandler;
    BoundEventAst _simpleHostEvent;
  
    /// Helper function to search for an event in [targetEventListeners] list and
    /// add a new one if it doesn't exist yet.
    /// TODO: try using Map, this code is quadratic and assumes typical event
  