# File src/ruby_supportlib/phusion_passenger/utils/hosts_file_parser.rb, line 39
      def initialize(filename_or_io = "/etc/hosts")
        if filename_or_io.respond_to?(:readline)
          read_and_parse(filename_or_io)
        else
          File.open(filename_or_io, "rb") do |f|
            read_and_parse(f)
          end
        end
      end