code: def test_map_category_string():
      a = Series(["a", "b", "c", "d"])
      b = Series(
          ["B", "C", "D", "E"],
          dtype="category",
          index=pd.CategoricalIndex(["b", "c", "d", "e"]),
      )
      c = Series(
          ["B", "C", "D", "E"], index=Index(["b", "c", "d", "e"])
      )
  
      exp = Series(
          pd.Categorical(
              [np.nan, "B", "C", "D"], categories=["B", "C", "D", "E"]
          )
      )
      tm.assert_series_equal(a.map(b), exp)
      exp = Series([np.nan, "B", "C", "D"])
      tm.assert_series_equal(a.map(c), exp)
  
imports: from collections import Counter, defaultdict
  from decimal import Decimal
  import math
  import numpy
  import pytest
  import pandas
  from pandas import DataFrame, Index, MultiIndex, Series, bdate_range, date_range, isna, timedelta_range
  import pandas._testing
label_desc: Use image node_id 15 for calling a global function with example usage: test_map_category_string() without return types