title: Implementation of the latest "Lookahead Optimizer" paper in Keras?
body: <p>The lookahead optimizer is proposed very recently (<a href="https://arxiv.org/abs/1907.08610" rel="nofollow noreferrer">https://arxiv.org/abs/1907.08610</a>), and seems very promising (even Hinton is one of the authors!).</p>
  
  <p>Therefore, I wonder how to <strong>implement it in keras</strong>? I think many people may need the answer to this question, because we want to plug it into our existing code and it may produce better results.</p>
  
  <p>I am new in keras, so any help would be truly appreciated. Thanks!</p>
  
  <p>p.s. source code of existing optimizers: <a href="https://github.com/keras-team/keras/blob/master/keras/optimizers.py" rel="nofollow noreferrer">https://github.com/keras-team/keras/blob/master/keras/optimizers.py</a></p>