@classmethod
def convert_transforms(cls, transforms):
    """
        Convert a stack of transforms to a format understood by the backend
        service.
        """
    backend_transforms = []
    for transform in transforms:
        converter = cls._transform_converters.get(transform.id)
        if not converter:
            converter = cls._transform_converters.get('__custom__')
        backend_transforms.append(converter(transform))
    return backend_transforms
