# File lib/mail/fields/common/parameter_hash.rb, line 11
    def [](key_name)
      pairs = select { |k,v| k =~ /^#{key_name}\*/ }
      pairs = pairs.to_a if RUBY_VERSION >= '1.9'
      if pairs.empty? # Just dealing with a single value pair
        super(key_name)
      else # Dealing with a multiple value pair or a single encoded value pair
        string = pairs.sort { |a,b| a.first <=> b.first }.map { |v| v.last }.join('')
        if mt = string.match(/([\w\d\-]+)'(\w\w)'(.*)/)
          string = mt[3]
          encoding = mt[1]
        else
          encoding = nil
        end
        Mail::Encodings.param_decode(string, encoding)
      end
    end