code: def test_TransferFunction_gain_margin():
      # Test for gain margin
      tf1 = TransferFunction(
          s**2, 5 * (s + 1) * (s - 5) * (s - 10), s
      )
      tf2 = TransferFunction(s**2 + 2 * s + 1, 1, s)
      tf3 = TransferFunction(1, a * s + b, s)
      tf4 = TransferFunction((s + 1) * exp(s / tau), s**2 + 2, s)
      tf_m = TransferFunctionMatrix([[tf2], [tf3]])
  
      assert gain_margin(tf1) == -20 * log(S(7) / 540) / log(10)
      assert gain_margin(tf2) == oo
  
      raises(NotImplementedError, lambda: gain_margin(tf4))
      raises(ValueError, lambda: gain_margin(tf3))
      raises(ValueError, lambda: gain_margin(MIMOSeries(tf_m)))
  
imports: from sympy.core.add import Add
  from sympy.core.function import Function
  from sympy.core.mul import Mul
  from sympy.core.numbers import I, pi, Rational, oo
  from sympy.core.power import Pow
  from sympy.core.singleton import S
  from sympy.core.symbol import symbols
  from sympy.functions.elementary.exponential import exp, log
  from sympy.functions.elementary.miscellaneous import sqrt
  from sympy.functions.elementary.trigonometric import atan
  from sympy.matrices.dense import eye
  from sympy.polys.polytools import factor
  from sympy.polys.rootoftools import CRootOf
  from sympy.simplify.simplify import simplify
  from sympy.core.containers import Tuple
  from sympy.matrices import ImmutableMatrix, Matrix, ShapeError
  from sympy.physics.control import TransferFunction, Series, Parallel, Feedback, TransferFunctionMatrix, MIMOSeries, MIMOParallel, MIMOFeedback, StateSpace, gbt, bilinear, forward_diff, backward_diff, phase_margin, gain_margin
  from sympy.testing.pytest import raises
label_desc: Use image node_id 28 for calling a global function with example usage: test_TransferFunction_gain_margin() without return types