code: def test_add_sequence(dtype):
      a = pd.array(["a", "b", None, None], dtype=dtype)
      other = ["x", None, "y", None]
  
      result = a + other
      expected = pd.array(["ax", None, None, None], dtype=dtype)
      tm.assert_extension_array_equal(result, expected)
  
      result = other + a
      expected = pd.array(["xa", None, None, None], dtype=dtype)
      tm.assert_extension_array_equal(result, expected)
  
imports: import operator
  import numpy
  import pytest
  from pandas.compat.pyarrow import pa_version_under12p0
  from pandas.core.dtypes.common import is_dtype_equal
  import pandas
  import pandas._testing
  from pandas.core.arrays.string_arrow import ArrowStringArray, ArrowStringArrayNumpySemantics
label_desc: Use image node_id 12 for calling a global function with example usage: test_add_sequence(dtype) without return types