title: keras "unknown loss function" error after defining custom loss function
body: <p>I defined a new loss function in keras in losses.py file. I close and relaunch anaconda prompt, but I got <code>ValueError: ('Unknown loss function', ':binary_crossentropy_2')</code>. I'm running keras using python2.7 and anaconda on windows 10.</p>
  
  <p>I temporarily solve it by adding the loss function in the python file I compile my model.</p>