# File lib/gettext/po.rb, line 150
    def has_key?(*arguments)
      case arguments.size
      when 1
        msgctxt = nil
        msgid = arguments[0]
      when 2
        msgctxt = arguments[0]
        msgid = arguments[1]
      else
        message = "has_key?: wrong number of arguments " +
                    "(#{arguments.size} for 1..2)"
        raise(ArgumentError, message)
      end
      id = [msgctxt, msgid]
      @entries.has_key?(id)
    end