old_contents: from setuptools import setup
  
  setup(
      name="klein",
      version="0.0.1",
      description="werkzeug + twisted.web",
      packages=["klein"],
      install_requires=["Twisted", "werkzeug"]
  )
  
new_contents: from setuptools import setup
  
  setup(
      name="klein",
      version="0.0.1",
      description="werkzeug + twisted.web",
      packages=["klein"],
      install_requires=["Twisted", "werkzeug", "mock"]
  )
  
subject: Add mock to setup.py