You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: mailto.rb
    path of file: ./repos/artichoke/artichoke-backend/src/extn/stdlib/uri/vendor/uri
    
    the code of the file until where you have to start completion: # frozen_string_literal: false
# = uri/mailto.rb
#
# Author:: Akira Yamada <akira@ruby-lang.org>
# License:: You can redistribute it and/or modify it under the same term as Ruby.
# Revision:: $I
    
    def initialize(*arg)
      super(*arg)

      @to = nil
      @headers = []

      # The RFC3986 parser does not normally populate opaque
      @opaque = "?#{@query}" if @query && !@opaque

      unless @opaque
        raise InvalidComponentError,
          "missing opaque part for mailto URL"
      end
      to, header = @opaque.split('?', 2)
      # allow semicolon as a addr-spec separator
      # http://support.microsoft.com/kb/820868
      unless /\A(?:[^@,;]+@[^@,;]+(?:\z|[,;]))*\z/ =~ to
        raise InvalidComponentError,
          "unrecognised opaque part for mailtoURL: #{@opaque}"
      end