kind=defined
names=optional?
visibility=public

--- optional?

Returns true if argument is optional.

   tobj = WIN32OLE_TYPE.new('Microsoft Excel 9.0 Object Library', 'Workbook')
   method = WIN32OLE_METHOD.new(tobj, 'SaveAs')
   param1 = method.params[0]
   puts "#{param1.name} #{param1.optional?}" # => Filename true

