code: def test_FourierSeries__add__sub():
      fo, fe, fp = _get_examples()
  
      assert fo + fo == fo.scale(2)
      assert fo - fo == 0
      assert -fe - fe == fe.scale(-2)
  
      assert (fo + fe).truncate() == 2 * sin(x) - sin(2 * x) - 4 * cos(
          x
      ) + cos(2 * x) + pi**2 / 3
      assert (fo - fe).truncate() == 2 * sin(x) - sin(2 * x) + 4 * cos(
          x
      ) - cos(2 * x) - pi**2 / 3
  
      assert isinstance(fo + 1, Add)
  
      raises(ValueError, lambda: fo + fourier_series(x, (x, 0, 2)))
  
imports: from sympy.core.add import Add
  from sympy.core.numbers import Rational, oo, pi
  from sympy.core.singleton import S
  from sympy.core.symbol import symbols
  from sympy.functions.elementary.exponential import exp, log
  from sympy.functions.elementary.piecewise import Piecewise
  from sympy.functions.elementary.trigonometric import cos, sin, sinc, tan
  from sympy.series.fourier import fourier_series
  from sympy.series.fourier import FourierSeries
  from sympy.testing.pytest import raises
  from functools import lru_cache
label_desc: Use image node_id 8 for calling a global function with example usage: test_FourierSeries__add__sub() without return types