code: def test_period_addsub_nat(self, freq):
      # GH#13071
      per = Period("2011-01", freq=freq)
  
      # For subtraction, NaT is treated as another Period object
      assert NaT - per is NaT
      assert per - NaT is NaT
  
      # For addition, NaT is treated as offset-like
      assert NaT + per is NaT
      assert per + NaT is NaT
  
imports: from datetime import timedelta
  import numpy
  import pytest
  from pandas._libs.tslibs.period import IncompatibleFrequency
  from pandas import NaT, Period, Timedelta, Timestamp, offsets
label_desc: Use image node_id 10 for calling the TestPeriodArithmetic obj's underlying member method code with example usage: obj.test_period_addsub_nat(freq) without return types