code: def create_item(attributes, to_ews_create_opts = {})
        template = Viewpoint::EWS::Template::CalendarItem.new attributes
        template.saved_item_folder_id = {id: self.id, change_key: self.change_key}
        rm = ews.create_item(template.to_ews_create(to_ews_create_opts)).response_messages.first
        if rm && rm.success?
          CalendarItem.new ews, rm.items.first[:calendar_item][:elems].first
        else
          raise EwsCreateItemError, "Could not create item in folder. #{rm.code}: #{rm.message_text}" unless rm
        end
      end
docs: Creates a new appointment
   @param attributes [Hash] Parameters of the calendar item. Some example attributes are listed below.
   @option attributes :subject [String]
   @option attributes :start [Time]
   @option attributes :end [Time]
   @return [CalendarItem]
   @see Template::CalendarItem