old_contents: #!/usr/bin/env python
  from os import path
  from IPython.html.nbextensions import install_nbextension
  from IPython.html.services.config import ConfigManager
  
  install_nbextension(
      path.join(path.dirname(path.abspath(__file__)), 'notebook_input_mode'), user=True, verbose=2)
  
  cm = ConfigManager().update('notebook', {"load_extensions": {"notebook_input_mode/main": True}})
  
new_contents: #!/usr/bin/env python
  from os import path
  
  from notebook.nbextensions import install_nbextension
  from notebook.services.config import ConfigManager
  
  install_nbextension(
      path.join(path.dirname(path.abspath(__file__)), 'notebook_input_mode'), user=True, verbose=2)
  
  cm = ConfigManager().update('notebook', {"load_extensions": {"notebook_input_mode/main": True}})
  
subject: Change imports in install.py to Jupyter4.x style