code: def test_drop_duplicate_cols():
      a = pd.Series(
          index=pd.date_range("2010-01-01", periods=5),
          data=100,
          name="a",
      )
      # second version of a w/ less data
      a2 = pd.Series(
          index=pd.date_range("2010-01-02", periods=4),
          data=900,
          name="a",
      )
      b = pd.Series(
          index=pd.date_range("2010-01-02", periods=5),
          data=200,
          name="b",
      )
      actual = ffn.merge(a, a2, b)
  
      assert actual["a"].shape[1] == 2
      assert len(actual.columns) == 3
  
      actual = actual.drop_duplicate_cols()
  
      assert len(actual.columns) == 2
      assert "a" in actual
      assert "b" in actual
      assert len(actual["a"].dropna()) == 5
  
imports: import ffn
  import pandas
  import numpy
  from pytest import fixture
  from numpy.testing import assert_almost_equal
label_desc: Use image node_id 26 for calling a global function with example usage: test_drop_duplicate_cols() without return types