code: def test_astype_bytes(self):
      # GH#39474
      result = Series(["foo", "bar", "baz"]).astype(bytes)
      assert result.dtypes == np.dtype("S3")
  
imports: from datetime import datetime, timedelta
  from importlib import reload
  import string
  import sys
  import numpy
  import pytest
  from pandas._libs.tslibs import iNaT
  import pandas.util._test_decorators
  from pandas import NA, Categorical, CategoricalDtype, DatetimeTZDtype, Index, Interval, NaT, Series, Timedelta, Timestamp, cut, date_range, to_datetime
  import pandas._testing
label_desc: Use image node_id 25 for calling the TestAstype obj's underlying member method code with example usage: obj.test_astype_bytes() without return types