title: how to pass a not like operator in a sqlalchemy ORM query
body: <p>I've got a query:  </p>
  
  <pre><code>MyModel.query.filter(Mymodel.name.contains('a_string'))
  </code></pre>
  
  <p>I need to do the same query but with the negation (a <strong>not like</strong> operator) but didn't find any operator matching my need in the <a href="http://www.sqlalchemy.org/docs/orm/tutorial.html#common-filter-operators" rel="noreferrer">SQLAlchemy documentation</a>.</p>
  
  <p>Is there any way to do it without using the sql part of SQLAlchemy???</p>