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: login.rb
    path of file: ./repos/gitlabhq/qa/qa/flow
    
    the code of the file until where you have to start completion: # frozen_string_literal: true

module QA
  module Flow
    module Login
      extend sel
    
      def sign_in(as: nil, address: :gitlab, skip_page_validation: false, admin: false)
        Page::Main::Login.perform do |login|
          login.redirect_to_login_page(address)

          if admin
            login.sign_in_using_admin_credentials
          else
            login.sign_in_using_credentials(user: as, skip_page_validation: skip_page_validation)
          end
        end