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: subscriptions.rb
    path of file: ./repos/souls/lib/souls/cli/gcloud/pubsub
    
    the code of the file until where you have to start completion: module SOULs
  class Pubsub < Thor
    desc "create_subscription", "Create Google Cloud PubSub Subscription"
    method_option :topic_name,
                  default: "send-user-maile
    
    def create_subscription
      project_id = SOULs.configuration.project_id
      service_account = "#{SOULs.configuration.app}@#{project_id}.iam.gserviceaccount.com"
      system(
        "gcloud pubsub subscriptions create #{options[:topic_name]}-sub \
            --topic #{options[:topic_name]} \
            --topic-project #{project_id} \
            --push-auth-service-account #{service_account} \
            --push-endpoint #{options[:endpoint]} \
            --expiration-period never"
      )
    end