code: def test_fill_corner(self, float_frame, float_string_frame):
      mf = float_string_frame
      mf.loc[mf.index[5:20], "foo"] = np.nan
      mf.loc[mf.index[-10:], "A"] = np.nan
  
      filled = float_string_frame.fillna(value=0)
      assert (filled.loc[filled.index[5:20], "foo"] == 0).all()
      del float_string_frame["foo"]
  
      float_frame.reindex(columns=[]).fillna(value=0)
  
imports: import numpy
  import pytest
  from pandas._config import using_pyarrow_string_dtype
  from pandas import Categorical, DataFrame, DatetimeIndex, NaT, PeriodIndex, Series, TimedeltaIndex, Timestamp, date_range, to_datetime
  import pandas._testing
  from pandas.tests.frame.common import _check_mixed_float
label_desc: Use image node_id 35 for calling the TestFillNA obj's underlying member method code with example usage: obj.test_fill_corner(float_frame, float_string_frame) without return types