code: def test_dataclass():
      est = Estimator(prediction_length=7)
  
      assert est.prediction_length == 7
      assert est.context_length == 14
      assert est.cardinality == [1]
  
file_path: gluonts/test/core/test_serde_dataclass.py
imports: from typing import List
  from gluonts.core import serde
  from gluonts.pydantic import BaseModel
label_desc: Use image node_id 1 for calling a global function with example usage: test_dataclass() without return types