code: def test_center(roll_func, kwargs, minp):
      obj = Series(np.random.default_rng(2).standard_normal(50))
      obj[:10] = np.nan
      obj[-10:] = np.nan
  
      result = getattr(
          obj.rolling(20, min_periods=minp, center=True), roll_func
      )(**kwargs)
      expected = (
          getattr(
              concat([obj, Series([np.nan] * 9)]).rolling(
                  20, min_periods=minp
              ),
              roll_func,
          )(**kwargs)
          .iloc[9:]
          .reset_index(drop=True)
      )
      tm.assert_series_equal(result, expected)
  
imports: from datetime import datetime
  import numpy
  import pytest
  import pandas.util._test_decorators
  from pandas import DataFrame, DatetimeIndex, Series, concat, isna, notna
  import pandas._testing
  from pandas.tseries import offsets
label_desc: Use image node_id 9 for calling a global function with example usage: test_center(roll_func, kwargs, minp) without return types