+ provider :facebook, FACEBOOK_AUTH_ID, FACEBOOK_AUTH_SECRET, facebook_options if defined?(FACEBOOK_AUTH_ID)
+ provider :windowslive, WINDOWSLIVE_AUTH_ID, WINDOWSLIVE_AUTH_SECRET, windowslive_options if defined?(WINDOWSLIVE_AUTH_ID)
+ provider :github, GITHUB_AUTH_ID, GITHUB_AUTH_SECRET, github_options if defined?(GITHUB_AUTH_ID)