docs: def watch():
      """Renerate documentation when it changes."""
  
      # Start with a clean build
      sphinx_build['-b', 'html', '-E', 'docs', 'docs/_build/html'] & FG
  
      handler = ShellCommandTrick(
          shell_command='sphinx-build -b html docs docs/_build/html',
          patterns=['*.rst', '*.py'],
          ignore_patterns=['_build/*'],
          ignore_directories=['.tox'],
          drop_during_process=True)
      observer = Observer()
      observe_with(observer, handler, pathnames=['.'], recursive=True)