code: def test_concat_string_index_name(myindex):
      # GH-Issue #3420
      data = {"a": [123, 456], "b": ["s1", "s2"]}
      df1 = gd.DataFrame(data).set_index(myindex)
      df2 = df1.copy()
      df3 = gd.concat([df1, df2])
  
      assert df3.index.name == myindex
  
imports: from decimal import Decimal
  import numpy
  import pandas
  import pytest
  import cudf
  from cudf.api.types import is_categorical_dtype
  from cudf.core._compat import PANDAS_GE_150, PANDAS_LT_140
  from cudf.core.dtypes import Decimal32Dtype, Decimal64Dtype, Decimal128Dtype
  from cudf.testing._utils import assert_eq, assert_exceptions_equal
label_desc: Use image node_id 11 for calling a global function with example usage: test_concat_string_index_name(myindex) without return types