code: def test_0_regression(self):
      from lightwood.mixer import NHitsMixer
  
      if NHitsMixer is not None:
          df = pd.read_csv("tests/data/arrivals.csv")
          target = "Traffic"
  
          pdef = ProblemDefinition.from_dict(
              {
                  "target": target,
                  "timeseries_settings": {
                      "order_by": "T",
                      "group_by": ["Country"],
                      "window": 4,
                      "horizon": 4,
                  },
              }
          )
          jai = json_ai_from_problem(df, pdef)
          jai.model["args"]["submodels"] = self.get_submodels()
          code = code_from_json_ai(jai)
          predictor = predictor_from_code(code)
  
          predictor.learn(df)
          predictor.predict(df, args={"fixed_confidence": 0.9})
  
file_path: lightwood/tests/unit_tests/mixer/test_nhits.py
imports: import unittest
  import numpy
  import pandas
  from lightwood.api.types import ProblemDefinition
  from lightwood.api.high_level import json_ai_from_problem, predictor_from_json_ai, JsonAI, code_from_json_ai, predictor_from_code
label_desc: Use image node_id 2 for calling the TestBasic obj's underlying member method code with example usage: obj.test_0_regression() without return types