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: user_service.rb
    path of file: ./repos/vets-api/modules/vaos/app/services/vaos
    
    the code of the file until where you have to start completion: # frozen_string_literal: true

require 'common/exceptions'

module VAOS
  class UserService < VAOS::BaseService
    def session(user)
      cached = cached_by_account_uuid(u
    
    def save_session!(account_uuid, token)
      session_store = SessionStore.new(
        account_uuid:,
        token:,
        unix_created_at: Time.now.utc.to_i
      )
      session_store.save
      session_store.expire(ttl_duration_from_token(token))
      token
    end