def real_ip(request):
    return request.META.get('HTTP_X_REAL_IP') or None
Append a single key-value pair to the `Entry` document. 
dataset/ETHPy150Open ulule/django-safety/safety/resolvers.py/real_ip--crossover with--dataset/ETHPy150Open swordapp/python-client-sword2/sword2/atom_objects.py/Entry.add_field