code: def test_period_sub_period_annual(self):
      left, right = Period("2011", freq="Y"), Period("2007", freq="Y")
      result = left - right
      assert result == 4 * right.freq
  
      msg = r"Input has different freq=M from Period\(freq=Y-DEC\)"
      with pytest.raises(IncompatibleFrequency, match=msg):
          left - Period("2007-01", freq="M")
  
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 4 for calling the TestPeriodArithmetic obj's underlying member method code with example usage: obj.test_period_sub_period_annual() without return types