code: def run(self):
      df = pd.DataFrame(dict(x=[1, 3, 4]))
      self.dump(df)
  
imports: import logging
  import unittest
  from unittest.mock import patch
  import luigi
  import pandas
  import gokart
label_desc: Use image node_id 1 for calling the DummyPandasDataFrameTask obj's underlying member method code with example usage: obj.run() without return types