docs: def create(self, instance, cidr_mask, description, **kwargs):
          """Create an ACL entry for the specified instance.
  
          :param str instance: The name of the instance to associate the new ACL entry with.
          :param str cidr_mask: The IPv4 CIDR mask for the new ACL entry.
          :param str description: A short description for the new ACL entry.
          :param collector kwargs: (optional) Additional key=value pairs to be supplied to the
              creation payload. **Caution:** fields unrecognized by the API will cause this request
              to fail with a 400 from the API.
          """
          # Build up request data.
          url = self._url.format(instance=instance)
          request_data = {
              'cidr_mask': cidr_mask,
              'description': description
          }
          request_data.update(kwargs)
  
          # Call to create an instance.
          response = requests.post(
              url,
              data=json.dumps(request_data),
              **self._default_request_kwargs
          )
  
          # Log outcome of instance creation request.
          if response.status_code == 200:
              logger.info('Successfully created a new ACL for instance {} with: {}.'
                          .format(instance, request_data))
          else:
              logger.info('Failed to create a new ACL for instance {} with: {}.'
                          .format(instance, request_data))
  
          data = self._get_response_data(response)
          return self._concrete_acl(data)