code: def test_GHFilterOrder():
      def fx(x):
          return 2 * x + 1
  
      f1 = GHFilterOrder(x0=array([0, 0]), dt=1, order=1, g=0.6, h=0.02)
      f2 = GHFilter(x=0, dx=0, dt=1, g=0.6, h=0.02)
  
      for i in range(100):
          z = fx(i) + randn()
          f1.update(z)
          f2.update(z)
  
          assert abs(f1.x[0] - f2.x) < 1.0e-18
  
file_path: filterpy/filterpy/gh/tests/test_gh.py
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  from filterpy.common import Saver
  from filterpy.gh import GHFilter, GHKFilter, least_squares_parameters, optimal_noise_smoothing, GHFilterOrder
  from numpy import array
  from numpy.random import randn
  import matplotlib.pyplot
label_desc: Use image node_id 5 for calling a global function with example usage: test_GHFilterOrder() and returns: unknown