def METHOD_NAME(self, x: Tuple[Tensor], data_samples: DetSampleList
                     ) -> Tuple[dict, DetSampleList]:
    """Perform forward propagation of the head, then calculate loss and
    predictions from the features and data samples.
    Args:
        x (tuple[Tensor]): Features from FPN.
        data_samples (list[:obj:`DetDataSample`]): Each item contains
            the meta information of each image and corresponding
            annotations.
    Returns:
        tuple: the return value is a tuple contains:
            - losses: (dict[str, Tensor]): A dictionary of loss components.
            - predictions (list[:obj:`InstanceData`]): Detection
              results of each image after the post process.
    """
    outs = self(x, data_samples)
    losses = self.module_loss(outs, data_samples)
    predictions = self.postprocessor(outs, data_samples, self.training)
    return losses, predictions