code: def test_least_squares():
      """there is an alternative form for computing h for the least squares.
      It works for all but the very first term (n=0). Use it to partially test
      the output of least_squares_parameters(). This test does not test that
      g is correct"""
  
      for n in range(1, 100):
          g, h = least_squares_parameters(n)
  
          h2 = 4 - 2 * g - (4 * (g - 2) ** 2 - 3 * g**2) ** 0.5
  
          assert abs(h2 - h) < 1.0e-12
  
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 1 for calling a global function with example usage: test_least_squares() without return types