title: Difference between shape and int_shape in Keras
body: <p>According to the Keras manual, </p>
  
  <p>keras.backend.shape() returns the symbolic shape of a tensor or variable.
  keras.backend.int_shape() returns the shape of tensor or variable as a tuple of int or None entries.</p>
  
  <p>These definitions are still unclear to me. I couldn't find any relevant material in Google, either. Can anyone help me understand the difference between the two?</p>