code: def test_concat_mixed_input():
      pdf1 = pd.DataFrame({"a": [10, 20, 30]})
      pdf2 = pd.DataFrame({"a": [11, 22, 33]})
  
      gdf1 = gd.from_pandas(pdf1)
      gdf2 = gd.from_pandas(pdf2)
  
      assert_eq(
          pd.concat([pdf1, None, pdf2, None]),
          gd.concat([gdf1, None, gdf2, None]),
          check_index_type=True,
      )
      assert_eq(
          pd.concat([pdf1, None]),
          gd.concat([gdf1, None]),
          check_index_type=True,
      )
      assert_eq(
          pd.concat([None, pdf2]),
          gd.concat([None, gdf2]),
          check_index_type=True,
      )
      assert_eq(
          pd.concat([None, pdf2, pdf1]),
          gd.concat([None, gdf2, gdf1]),
          check_index_type=True,
      )
  
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 17 for calling a global function with example usage: test_concat_mixed_input() without return types