code: def test_melt_mixed_int_str_value_vars(self):
      # GH 29718
      df = DataFrame({0: ["foo"], "a": ["bar"]})
      result = melt(df, value_vars=[0, "a"])
      expected = DataFrame(
          {"variable": [0, "a"], "value": ["foo", "bar"]}
      )
      tm.assert_frame_equal(result, expected)
  
imports: import re
  import numpy
  import pytest
  import pandas
  from pandas import DataFrame, Index, date_range, lreshape, melt, wide_to_long
  import pandas._testing
label_desc: Use image node_id 18 for calling the TestMelt obj's underlying member method code with example usage: obj.test_melt_mixed_int_str_value_vars() without return types