          if self._ACCEPT_QUERY_PARAM and request.GET.get(self._ACCEPT_QUERY_PARAM, None):
              # Use _accept parameter override
              accept_list = [request.GET.get(self._ACCEPT_QUERY_PARAM)]
          elif (self._IGNORE_IE_ACCEPT_HEADER and
                request.META.has_key('HTTP_USER_AGENT') and
                MSIE_USER_AGENT_REGEX.match(request.META['HTTP_USER_AGENT'])):
              # Ignore MSIE's broken accept behavior and do something sensible instead
              accept_list = ['text/html', '*/*']
          elif request.META.has_key('HTTP_ACCEPT'):
              # Use standard HTTP Accept negotiation
 
</s> remove             accept_list = [token.strip() for token in request.META["HTTP_ACCEPT"].split(',')]
 </s> add             accept_list = [token.strip() for token in request.META['HTTP_ACCEPT'].split(',')] </s> remove         elif request.META.has_key('HTTP_ACCEPT'):
 </s> add         elif 'HTTP_ACCEPT' in request.META:
              'HTTP_USER_AGENT' in request.META and
          if self._ACCEPT_QUERY_PARAM and request.GET.get(self._ACCEPT_QUERY_PARAM, None):
              # Use _accept parameter override
              accept_list = [request.GET.get(self._ACCEPT_QUERY_PARAM)]
          elif (self._IGNORE_IE_ACCEPT_HEADER and
              'HTTP_USER_AGENT' in request.META and
                MSIE_USER_AGENT_REGEX.match(request.META['HTTP_USER_AGENT'])):
              # Ignore MSIE's broken accept behavior and do something sensible instead
              accept_list = ['text/html', '*/*']
          elif request.META.has_key('HTTP_ACCEPT'):
              # Use standard HTTP Accept negotiation
keep keep keep keep replace keep keep keep keep keep
 Replace 'x.has_key(y)' with 'y in x' 
djangorestframework/mixins.py