old_contents: import numpy as np
  
  from setuptools import setup
  from setuptools import setup, Extension
  from Cython.Distutils import build_ext
  
  kendalltau = Extension('cstats.kendalltau',
                         sources = ['cstats/kendalltau.pyx'],
                         include_dirs = [np.get_include()],)
  setup(
          packages = ['cstats'],
          name = "cstats",
          version = "0.1",
          ext_modules = [kendalltau],
          cmdclass = {'build_ext': build_ext},
          install_requires=[
              "numpy",
              "cython"
          ]
  )
  
  
new_contents: import numpy as np
  
  from setuptools import setup, Extension
  from Cython.Distutils import build_ext
  
  kendalltau = Extension('cstats.kendalltau',
                         sources = ['cstats/kendalltau.pyx'],
                         include_dirs = [np.get_include()],)
  setup(
          packages = ['cstats'],
          name = "cstats",
          version = "0.1",
          ext_modules = [kendalltau],
          cmdclass = {'build_ext': build_ext},
          install_requires=[
              "numpy",
              "cython"
          ]
  )
  
  
subject: Remove extra from setuptools.