Make class variable local

hpib.py

@@ -172,9 +172,9 @@ class HpibDevice(object):
         time.sleep(self._pause)
 
     def query(self, queryStr):
-        self._answerStr = self._port.query(self._hpib_address, queryStr)
+        answerStr = self._port.query(self._hpib_address, queryStr)
         self.set_local(self._keepLocal)
-        return self._answerStr
+        return answerStr
 
     def get_devices(self):
         return ["Not implemented"]