code: def test_combine_first_int(self):
      # GH14687 - integer series that do no align exactly
  
      df1 = DataFrame({"a": [0, 1, 3, 5]}, dtype="int64")
      df2 = DataFrame({"a": [1, 4]}, dtype="int64")
  
      result_12 = df1.combine_first(df2)
      expected_12 = DataFrame({"a": [0, 1, 3, 5]})
      tm.assert_frame_equal(result_12, expected_12)
  
      result_21 = df2.combine_first(df1)
      expected_21 = DataFrame({"a": [1, 4, 3, 5]})
      tm.assert_frame_equal(result_21, expected_21)
  
imports: from datetime import datetime
  import numpy
  import pytest
  from pandas.core.dtypes.cast import find_common_type
  from pandas.core.dtypes.common import is_dtype_equal
  import pandas
  from pandas import DataFrame, Index, MultiIndex, Series
  import pandas._testing
label_desc: Use image node_id 16 for calling the TestDataFrameCombineFirst obj's underlying member method code with example usage: obj.test_combine_first_int() without return types