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: dialog.rb
    path of file: ./repos/view_components/app/components/primer/alpha
    
    the code of the file until where you have to start completion: # frozen_string_literal: true

module Primer
  module Alpha
    # A `Dialog` is used to remove the user from the main application flow,
    # to confirm actions, ask for disambiguation or to present small forms.
    #
    # @accessibility
    #   - **Dialog Accessible Name**: A dialog should have an accessible name,
    #   so screen readers are a
    
      def initialize(
        title:,
        subtitle: nil,
        size: DEFAULT_SIZE,
        position: DEFAULT_POSITION,
        position_narrow: DEFAULT_POSITION_NARROW,
        visually_hide_title: false,
        id: self.class.generate_id,
        **system_arguments
      )
        @system_arguments = deny_tag_argument(**system_arguments)

        @id = id.to_s
        @title = title
        @subtitle = subtitle
        @size = size
        @position = position
        @position_narrow = position_narrow
        @visually_hide_title = visually_hide_title

        @system_arguments[:tag] = "dialog"
        @system_arguments[:id] = @id
        @system_arguments[:aria] = { modal: true }
        @system_arguments[:aria] = merge_aria(
          @system_arguments, {
            aria: {
              labelledby: labelledby,
              describedby: "#{@id}-description"
            }
          }
        )
        @system_arguments[:classes] = class_names(
          "Overlay",
          "Overlay-whenNarrow",
          SIZE_MAPPINGS[fetch_or_fallback(SIZE_OPTIONS, @size, DEFAULT_SIZE)],
          "Overlay--motion-scaleFade",
          POSITION_MAPPINGS[fetch_or_fallback(POSITION_OPTIONS, @position, DEFAULT_POSITION)],
          POSITION_NARROW_MAPPINGS[fetch_or_fallback(POSITION_NARROW_MAPPINGS, @position_narrow, DEFAULT_POSITION_NARROW)],
          system_arguments[:classes]
        )
      end