def validate(self):
        """ Checks whether the backbone string is correct.
        """
        allowed_backbones = ['EfficientNetB0', 'EfficientNetB1', 'EfficientNetB2', 'EfficientNetB3', 'EfficientNetB4',
                             'EfficientNetB5', 'EfficientNetB6', 'EfficientNetB7']
        backbone = self.backbone.split('_')[0]

        if backbone not in allowed_backbones:
            raise ValueError('Backbone (\'{}\') not in allowed backbones ({}).'.format(backbone, allowed_backbones))
 Checks whether the backbone string is correct.
        
keras_retinanet/models/effnet.py