@@ -135,7 +135,7 @@ class ResultContainer(object):
135135 self._number_of_results = []
136136 self._ordered = False
137137 self.paging = False
138− self.unresponsive_engines = []
138+ self.unresponsive_engines = set()
139139
140140 def extend(self, engine_name, results):
141141 for result in list(results):
@@ -306,5 +306,5 @@ class ResultContainer(object):
306306 return 0
307307 return resultnum_sum / len(self._number_of_results)
308308
309− def add_unresponsive_engine(self, engine_name):
310− self.unresponsive_engines.append(engine_name)
309+ def add_unresponsive_engine(self, engine_error):
310+ self.unresponsive_engines.add(engine_error)