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: document.rb
    path of file: ./repos/puredocx/lib/puredocx
    
    the code of the file until where you have to start completion: module PureDocx
  class Document
    attr_accessor :body_
    
    def save!
      rels_constructor.prepare_basic_rels!
      DocArchive.open(file_path, rels_constructor.rels) do |file|
        file.add('[Content_Types].xml', DocArchive.template_path('[Content_Types].xml'))
        file.save_rels
        file.save_document_content(body_content, header_content, pagination_position)
      end
    end