title: Error with sessionmaker
body: <p>I can see from this question <a href="https://stackoverflow.com/questions/3221814/why-are-session-methods-unbound-in-sqlalchemy-using-sqlite">Why are session methods unbound in sqlalchemy using sqlite?</a> that I need to instantiate the class for sessionmaker. </p>
  
  <p>I get the same error, and I assume the 'fix' will work, only I have no idea how to 'instantiate the class'</p>
  
  <p>My set up code is as per the linked question. </p>
  
  <p>From this question <a href="https://stackoverflow.com/questions/396856/how-to-instantiate-a-class-in-python">How to instantiate a class in python</a> I can see that I need to call the class object, and my erroneous assumption is that the:</p>
  
  <pre><code>session = sessionmaker(bind=engine)
  </code></pre>
  
  <p>line is the instantiation.</p>