code: function flatten(className, value) {
        var pairs
        var pair
        var index
        var length
  
        if (language[keyInsensitive]) {
          value = value.toLowerCase()
        }
  
        pairs = value.split(space)
        length = pairs.length
        index = -1
  
        while (++index < length) {
          pair = pairs[index].split(verticalBar)
  
          compiledKeywords[pair[0]] = [className, pair[1] ? Number(pair[1]) : 1]
        }
      }
docs: Flatten a classname.