docs: def codemirror_field_css_bundle(field):
      """
      Filter to get CodeMirror CSS bundle name needed for a single field.
  
      Example:
          ::
  
          {% load djangocodemirror_tags %}
          {{ form.myfield|codemirror_field_css_bundle }}
  
      Arguments:
          field (djangocodemirror.fields.CodeMirrorField): A form field.
  
      Raises:
          CodeMirrorFieldBundleError: Raised if Codemirror configuration from
          field does not have a bundle name.
  
      Returns:
          string: Bundle name to load with webassets.
      """
      manifesto = CodemirrorAssetTagRender()
      manifesto.register_from_fields(field)
  
      try:
          bundle_name = manifesto.css_bundle_names()[0]
      except IndexError:
          msg = ("Given field with configuration name '{}' does not have a "
                 "Javascript bundle name")
          raise CodeMirrorFieldBundleError(msg.format(field.config_name))
  
      return bundle_name