new_contents: from invoke import task, run
  
  _run = run
  
  def run(*args, **kwargs):
      kwargs.update(echo=True)
      return _run(*args, **kwargs)
  
  @task
  def clean():
      run("find . -name '*.so' -delete")
      run("rm -rf kmeans.egg-info")
      run("rm -rf build/")
  
  @task('clean')
  def build():
      run("python setup.py develop")
  
  @task('clean')
  def pypi():
      run('python setup.py sdist upload')
  
  @task('clean')
  def test():
      run('tox')
  
subject: Add invoke tasks