def METHOD_NAME(self):
    input_dict = {
        "task_specific_params": {
            "summarization": {"length_penalty": 1.0, "max_length": 128, "min_length": 12, "num_beams": 4},
            "summarization_cnn": {"length_penalty": 2.0, "max_length": 142, "min_length": 56, "num_beams": 4},
            "summarization_xsum": {"length_penalty": 1.0, "max_length": 62, "min_length": 11, "num_beams": 6},
        }
    }
    expected_dict = {
        "task_specific_params.summarization.length_penalty": 1.0,
        "task_specific_params.summarization.max_length": 128,
        "task_specific_params.summarization.min_length": 12,
        "task_specific_params.summarization.num_beams": 4,
        "task_specific_params.summarization_cnn.length_penalty": 2.0,
        "task_specific_params.summarization_cnn.max_length": 142,
        "task_specific_params.summarization_cnn.min_length": 56,
        "task_specific_params.summarization_cnn.num_beams": 4,
        "task_specific_params.summarization_xsum.length_penalty": 1.0,
        "task_specific_params.summarization_xsum.max_length": 62,
        "task_specific_params.summarization_xsum.min_length": 11,
        "task_specific_params.summarization_xsum.num_beams": 6,
    }
    self.assertEqual(flatten_dict(input_dict), expected_dict)