code: def test_combine_first(self):
      pdf = pd.DataFrame(
          {
              "A": {"falcon": 330.0, "eagle": 160.0},
              "B": {"falcon": 345.0, "eagle": 200.0, "duck": 30.0},
          }
      )
      pser1, pser2 = pdf.A, pdf.B
      psdf = ps.from_pandas(pdf)
      psser1, psser2 = psdf.A, psdf.B
  
      self.assert_eq(
          psser1.combine_first(psser2), pser1.combine_first(pser2)
      )
  
      psser1.name = pser1.name = ("X", "A")
      psser2.name = pser2.name = ("Y", "B")
  
      self.assert_eq(
          psser1.combine_first(psser2), pser1.combine_first(pser2)
      )
  
imports: import unittest
  from collections import defaultdict
  import inspect
  from datetime import datetime, timedelta
  import numpy
  import pandas
  from pyspark.ml.linalg import SparseVector
  from pyspark import pandas
  from pyspark.testing.pandasutils import PandasOnSparkTestCase, SPARK_CONF_ARROW_ENABLED
  from pyspark.testing.sqlutils import SQLTestUtils
  from pyspark.pandas.exceptions import PandasNotImplementedError
  from pyspark.pandas.missing.series import MissingPandasLikeSeries
  from pyspark.pandas.typedef.typehints import extension_object_dtypes_available
label_desc: Use image node_id 42 for calling the SeriesTestsMixin obj's underlying member method code with example usage: obj.test_combine_first() without return types