code: def test_sign_test():
      x = [7.8, 6.6, 6.5, 7.4, 7.3, 7.0, 6.4, 7.1, 6.7, 7.6, 6.8]
      M, p = sign_test(x, mu0=6.5)
      # from R SIGN.test(x, md=6.5)
      # from R
      assert_almost_equal(p, 0.02148, 5)
      # not from R, we use a different convention
      assert_equal(M, 4)
  
file_path: statsmodels/statsmodels/stats/tests/test_descriptivestats.py
imports: import numpy
  from numpy.testing import assert_almost_equal, assert_equal
  import pandas
  import scipy.stats
  import pytest
  from statsmodels.iolib.table import SimpleTable
  from statsmodels.stats.descriptivestats import Description, describe, sign_test
label_desc: Use image node_id 2 for calling a global function with example usage: test_sign_test() without return types