code: def authenticate(self, request):
          
  
          # todo: can we trust that request.user variable is even defined?
          if request.user and request.user.is_authenticated():
              return request.user
  
          if 'HTTP_AUTHORIZATION' in request.META:
              auth = request.META['HTTP_AUTHORIZATION'].split()
              if len(auth) == 2:
                  if auth[0].lower() == "basic":
                      uname, passwd = base64.b64decode(auth[1]).split(':')
                      user = authenticate(username=uname, password=passwd)
                      if user is not None:
                          if user.is_active:
                              request.user = user
                              return user
                      else:
                          raise Forbidden()
  
          # either no auth header or using some other auth protocol,
          # we'll return a challenge for the user anyway
          raise Unauthorized()
docs: Authenticate request using HTTP Basic authentication protocl.
  
          If the user is successfully identified, the corresponding user
          object is stored in `request.user`. If the request has already
          been authenticated (i.e. `request.user` has authenticated user
          object), this function does nothing.
  
          Raises Forbidden or Unauthorized if the user authentication
          fails. If no exception is thrown, the `request.user` will
          contain authenticated user object.