code: def test_groupby_reset_index_dtype():
      # Make sure int8 dtype is properly preserved
      # Through various cudf/dask_cudf ops
      #
      # Note: GitHub Issue#4090 reproducer
  
      df = cudf.DataFrame()
      df["a"] = np.arange(10, dtype="int8")
      df["b"] = np.arange(10, dtype="int8")
      df = dask_cudf.from_cudf(df, 1)
  
      a = df.groupby("a").agg({"b": ["count"]})
  
      assert a.index.dtype == "int8"
      assert a.reset_index().dtypes[0] == "int8"
  
imports: import numpy
  import pandas
  import pytest
  import dask
  from dask import dataframe
  from dask.utils_test import hlg_layer
  import cudf
  import dask_cudf
  from dask_cudf.groupby import OPTIMIZED_AGGS, _aggs_optimized
label_desc: Use image node_id 18 for calling a global function with example usage: test_groupby_reset_index_dtype() without return types