code: def test_FourierSeries__neg():
      fo, fe, fp = _get_examples()
  
      assert (-fo).truncate() == -2 * sin(x) + sin(2 * x) - (
          2 * sin(3 * x) / 3
      )
      assert (-fe).truncate() == +4 * cos(x) - cos(2 * x) - pi**2 / 3
  
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 7 for calling a global function with example usage: test_FourierSeries__neg() without return types