code: def test_objarr_radd_str(self, box_with_array):
      ser = Series(["x", np.nan, "x"])
      expected = Series(["ax", np.nan, "ax"])
  
      ser = tm.box_expected(ser, box_with_array)
      expected = tm.box_expected(expected, box_with_array)
  
      result = "a" + ser
      tm.assert_equal(result, expected)
  
imports: import datetime
  from decimal import Decimal
  import operator
  import numpy
  import pytest
  from pandas._config import using_pyarrow_string_dtype
  import pandas.util._test_decorators
  import pandas
  from pandas import Series, Timestamp, option_context
  import pandas._testing
  from pandas.core import ops
label_desc: Use image node_id 5 for calling the TestArithmetic obj's underlying member method code with example usage: obj.test_objarr_radd_str(box_with_array) without return types