Ruby on Rails

NoMethodError: undefined method `set' for main:Object

/apps/app_a/production/releases/20151222191024/config/environments/production.rb:2:in 

>>production.rb

set :sidekiq_role, :app

set :sidekiq_config, "#{current_path}/config/sidekiq.yml"  

set :sidekiq_env, 'production'

set :deploy_to, "/apps/app_a/production"

set :rails_env, "production"

set :stage, 'production'

set :branch, "master"

set :whenever_environment, 'production'

set :whenever_identifier, "production"