Method then

lib/lazy-result.js:439–450

(onFulfilled, onRejected)

  }

  then(onFulfilled, onRejected) {
    if (process.env.NODE_ENV !== 'production') {
      if (!('from' in this.opts)) {
        warnOnce(
          'Without `from` option PostCSS could generate wrong source map ' +
            'and will not find Browserslist config. Set it to CSS file path ' +
            'or to `undefined` to prevent this warning.'
        )
      }
    }
    return this.async().then(onFulfilled, onRejected)
  }

  toString() {
    return this.css