old_contents: from athenet.algorithm.derest.activation import count_activation
  from athenet.algorithm.derest.derivative import count_derivative
  
  
  class DerestLayer(object):
  
      def __init__(self, layer):
          self.layer = layer
          self.activations = None
          self.derivatives = None
  
      def count_activation(self, input):
          return count_activation(input, self.layer)
  
      def count_derivatives(self, output, input_shape):
          #TODO - nice check if activations are done
          return count_derivative(output, self.activations,
                                  input_shape, self.layer)
  
      def count_derest(self, f):
          pass
  
new_contents: class DerestLayer(object):
  
      def __init__(self, layer):
          self.layer = layer
          self.activations = None
          self.derivatives = None
  
      def count_activation(self, input):
          raise NotImplementedError
  
      def count_derivatives(self, output, input_shape):
          #TODO - nice check if activations are done
          raise NotImplementedError
  
      def count_derest(self, f):
          return []
  
subject: fix in derest.layers