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: sirene_client.rb
    path of file: ./repos/ekylibre/lib/clients/insee
    
    the code of the file until where you have to start completion: module Clients
  module Insee
    class SireneClient
      TOKEN_URL = 'https:/
    
        def token
          key64 = Base64.strict_encode64("#{key}:#{secret}")
          auth_key = "Basic #{key64}"
          call = RestClient.post(TOKEN_URL, { grant_type: 'client_credentials' }, { authorization: auth_key } )
          response = JSON.parse(call.body).deep_symbolize_keys
          response[:access_token]
        end