code: function guessFontWeight(basename) {
    return basename
      .split('-')
      .slice(1)
      .map(item => item.toLowerCase())
      .reduce((prev, item) => {
        if (item === 'normal') {
          return prev
        }
  
        if (fontWeightNames[item]) {
          return `font-weight:${fontWeightNames[item]};`
        }
  
        if (fontWeightKeywords.indexOf(item) >= 0) {
          return `font-weight:${item};`
        }
  
        return prev
      }, '')
  }
docs: Guess the `font-weight` property from the font file name.
  @param  {String} basename Font base filename.
  @return {String}          `font-weight` property and guessed value.