def has_header(self, header):
        return self._headers.has_key(header.lower())
add another list-like object to self
dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-1.2/django/http/__init__.py/HttpResponse.has_header--crossover with--dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-1.5/django/contrib/gis/geos/mutable_list.py/ListMixin.__iadd__