def __init__(self, num_classes):
    """Constructor.

    Args:
      num_classes: number of classes.  Note that num_classes *does not* include
      background categories that might be implicitly predicted in various
      implementations.
    """
    self._num_classes = num_classes
    self._groundtruth_lists = {}

    super(DetectionModel, self).__init__()
Constructor.

    Args:
      num_classes: number of classes.  Note that num_classes *does not* include
      background categories that might be implicitly predicted in various
      implementations.
    
inference_api/src/main/object_detection/core/model.py