def __init__(self, generator, tensorboard=None, threshold=0.05):
        """ CocoEval callback intializer.

        Args
            generator   : The generator used for creating validation data.
            tensorboard : If given, the results will be written to tensorboard.
            threshold   : The score threshold to use.
        """
        self.generator = generator
        self.threshold = threshold
        self.tensorboard = tensorboard

        super(CocoEval, self).__init__()
 CocoEval callback intializer.

        Args
            generator   : The generator used for creating validation data.
            tensorboard : If given, the results will be written to tensorboard.
            threshold   : The score threshold to use.
        
keras_retinanet/callbacks/coco.py