module Devise::Models::Rememberable

def rememberable_value
  if respond_to?(:remember_token)
    remember_token
  elsif respond_to?(:authenticatable_salt) && (salt = authenticatable_salt.presence)
    salt
  else
    raise "authenticatable_salt returned nil for the #{self.class.name} model. " \
      "In order to use rememberable, you must ensure a password is always set " \
      "or have a remember_token column in your model or implement your own " \
      "rememberable_value in the model with custom logic."
  end
end