fix mentor's comment 2

app/models/user.rb

@@ -24,7 +24,7 @@ class User < ApplicationRecord
     SecureRandom.urlsafe_base64
     SecureRandom.urlsafe_base64
   end
   end
 
 
-  def User.digest(token)
+  def self.digest(token)
     Digest::SHA1.hexdigest(token.to_s)
     Digest::SHA1.hexdigest(token.to_s)
   end
   end