code: def test_na_values_with_dtype_str_and_na_filter(
      all_parsers, na_filter
  ):
      # see gh-20377
      parser = all_parsers
      data = "a,b,c\n1,,3\n4,5,6"
  
      # na_filter=True --> missing value becomes NaN.
      # na_filter=False --> missing value remains empty string.
      empty = np.nan if na_filter else ""
      expected = DataFrame(
          {"a": ["1", "4"], "b": [empty, "5"], "c": ["3", "6"]}
      )
  
      result = parser.read_csv(
          StringIO(data), na_filter=na_filter, dtype=str
      )
      tm.assert_frame_equal(result, expected)
  
imports: from io import StringIO
  import numpy
  import pytest
  from pandas._libs.parsers import STR_NA_VALUES
  from pandas import DataFrame, Index, MultiIndex
  import pandas._testing
label_desc: Use image node_id 23 for calling a global function with example usage: test_na_values_with_dtype_str_and_na_filter(all_parsers, na_filter) without return types