docs: def install(ctx, plugin):
      """
      Install the given plugin.
      """
      ensure_inside_venv(ctx)
  
      plugin_name = get_plugin_name(plugin)
      try:
          info = get_plugin_info(plugin_name)
      except NameError:
          echo_error("Plugin {} could not be found.".format(plugin))
          sys.exit(1)
      except ValueError as e:
          echo_error("Unable to retrieve plugin info. "
                     "Error was:\n\n {}".format(e))
          sys.exit(1)
  
      try:
          installed_version = pkg_resources.get_distribution(plugin_name).version
      except pkg_resources.DistributionNotFound:
          installed_version = None
  
      if installed_version is not None and info['version'] == installed_version:
          click.echo("You already have the latest version of {} ({}).".format(
              plugin, info['version']
          ))
          return
  
      pinned_plugin = '{0}=={1}'.format(plugin_name, info['version'])
      try:
          run_command([sys.executable, '-m', 'pip', 'install', pinned_plugin])
      except subprocess.CalledProcessError as e:
          echo_error("Error when trying to install plugin {}. "
                     "Error was:\n\n {}".format(plugin, e))
          sys.exit(1)
  
      echo_success("Plugin {} {} installed successfully.".format(
          plugin, info['version']
      ))