code: def watch_docs(ctx, browse=False):
      
      try:
          import sphinx_autobuild  # noqa
      except ImportError:
          print('ERROR: watch task requires the sphinx_autobuild package.')
          print('Install it with:')
          print('    pip install sphinx-autobuild')
          sys.exit(1)
      ctx.run('sphinx-autobuild {0} {1} {2} -z marshmallow'.format(
          '--open-browser' if browse else '', docs_dir, build_dir), echo=True, pty=True)
docs: Run build the docs when a file changes.