code: function params (str){
        return reduce(str.split(/ *; */), function (obj, str){
          var parts = str.split(/ *= */),
              key = parts.shift(),
              val = parts.shift()
  
          if (key && val) obj[key] = val
          return obj
        }, {})
      }
docs: Return header field parameters.
  
  @param {String} str
  @return {Object}
  @api private