code: def _get_examples():
      fo = fourier_series(x, (x, -pi, pi))
      fe = fourier_series(x**2, (-pi, pi))
      fp = fourier_series(
          Piecewise((0, x < 0), (pi, True)), (x, -pi, pi)
      )
      return fo, fe, fp
  
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 1 for calling a global function with example usage: _get_examples() and returns: fo,  fe,  fp