title: How to Fetch all Entity Types in AppEngine
body: <p>How can I retrieve all of the entity types from the datastore in appengine? For examaple, in my ORM I have defined:</p>
  
  <pre><code>class Person(db.Model):
    # fields here...
  
  class Employee(db.Model):
    # fields here...
  </code></pre>
  
  <p>I want a way to get "Employee" and "Person" in a list, but not the actual data.</p>
  
  <p>Thanks in advance!</p>