title: Scope block ArgumentError with associations.
body: <p>I have a join table between Folders and Emails, and I have a user_id also in my join tables model. In essence:</p>
  
  <pre><code>class Folder &lt; ActiveRecord::Base
    has_many :folder_emails,
             :class_name =&gt; "FolderEmail"
  
    has_many :emails, -&gt;(user) { where user_id: user.id }, :through =&gt; :folder_emails
  end
  </code></pre>
  
  <p>So, when I try to do <code>Folder.find(1)</code>, I get the error:
  <code>ArgumentError: wrong number of arguments (3 for 1..2)</code></p>
  
  <p>I'm new to the -> scope block syntax, and I can't comprehend why I'm getting this error.</p>