def __call__(self, sample, context=None):
        """ Process a sample.
        Args:
            sample (dict): a dict of sample, eg: {'image':xx, 'label': xxx}
            context (dict): info about this sample processing
        Returns:
            result (dict): a processed sample
        """
        if isinstance(sample, Sequence):  # for batch_size
            for i in range(len(sample)):
                sample[i] = self.apply(sample[i], context)
        else:
            # image.shape changed
            sample = self.apply(sample, context)
        return sample
 Process a sample.
        Args:
            sample (dict): a dict of sample, eg: {'image':xx, 'label': xxx}
            context (dict): info about this sample processing
        Returns:
            result (dict): a processed sample
        
ppdet/data/transform/keypoints_3d_operators.py