code: def validate(self, value, request):
          
  
          from django.http import HttpResponseBadRequest
          from doac.http import HttpResponseUnauthorized
          
          if not value:
              response = HttpResponseBadRequest()
              response["WWW-Authenticate"] = request_error_header(CredentialsNotProvided)
              
              return response
          
          try:
              access_token = AccessToken.objects.for_token(value)
          except AccessToken.DoesNotExist:
              response = HttpResponseUnauthorized()
              response["WWW-Authenticate"] = request_error_header(InvalidToken)
              
              return response
          
          return None
docs: Try to get the `AccessToken` associated with the given token.
  
          The return value is determined based n a few things:
  
          - If no token is provided (`value` is None), a 400 response will  be returned.
          - If an invalid token is provided, a 401 response will be returned.
          - If the token provided is valid, `None` will be returned.