How to use the fela-tools.generateCSSSelector function in fela-tools

)
          } else {
            // TODO: warning
          }
        } else if (!isUndefinedValue(value)) {
          ruleset[property] = value
        }

        return ruleset
      },
      {}
    )

    if (Object.keys(ruleSet).length > 0) {
      const css = cssifyObject(ruleSet)
      const selector = generateCSSSelector(className, pseudo)
      const cssRule = generateCSSRule(selector, css)

      if (media.length > 0) {
        if (!renderer.mediaRules.hasOwnProperty(media)) {
          renderer.mediaRules[media] = ''
        }

        renderer.mediaRules[media] += cssRule
      } else {
        renderer.rules += cssRule
      }

      renderer._emitChange({
        selector,
        declaration: css,
        media,