title: How to switch Backend with Keras (from TensorFlow to Theano)
body: <p>I tried to switch Backend with Keras (from TensorFlow to Theano) but did not manage.
  I followed the temps described <a href="https://keras.io/backend/" rel="noreferrer">here</a> but it doesn't work. I created a keras.json in the keras' directory (as it did not exist) but it doesn't change anything when I import it from Python.</p>