Rails authentication checks
Another view on @tokland solution:

def authenticate!
  return fail! unless account = Account.find_by(subdomain: subdomain)
  return fail! unless user = account.users.find_by(email: params["user"]["email"])
  return fail! unless user.authenticate(params["user"]["password"])
  success! user
end


This intention is to be as close to "original task explained in common English" as possible. And return keyword allows me to do that.