code: def write_init_files(packages):
      
      init_text = """__path__ = __import__('pkgutil').extend_path(__path__, __name__)
  
  try:
      from .__doc__ import __doc__
  except ImportError:
      pass
  """
      for package in packages:
          path = os.path.join('src', package.replace('.', os.sep), '__init__.py')
          if os.path.exists(path):
              with open(path) as f:
                  old_text = f.read()
          else:
              old_text = ''
          if old_text != init_text:
              with open(path, 'w') as f:
                  f.write(init_text)
docs: Make sure package hierarchy is a "pkgutil-style namespace
      package". For more detail see
      https://packaging.python.org/guides/packaging-namespace-packages/