title: How to get peewee result length
body: <p>I use peewee orm in python. </p>
  
  <p>I have a query that : </p>
  
  <pre><code>userOrganizations = (UserOrganization
      .select(UserOrganization,Organization)
      .join(Organization)
      .where(UserOrganization.user==user.user_id)
      .aggregate_rows()
  )
  </code></pre>
  
  <p>I want to get length of userOrganizations variable. Is there any method like userOrganizations.length() ? </p>