def qvalue(media_type)
      return 1 if @qvalues.empty?
      m = matches(media_type)
      return 0 if m.empty?
      normalize_qvalue(@qvalues[m.first])
    end
def qvalue(media_type)
      return 1 if @qvalues.empty?
      m = matches(media_type)
      return 0 if m.empty?
      normalize_qvalue(@qvalues[m.first])
    end
Determines the quality factor (qvalue) of the given +media_type+.