def forward_prop_this_layer(self, A_prev, W_curr, b_curr, activation_function):
    z_curr = np.dot(W_curr, A_prev) + b_curr

    if activation_function is 'relu':
      activation = relu
    elif activation_function is 'sigmoid':
      activation = sigmoid
    else:
      raise Exception(f"{activation_function} is currently not supported, Only sigmoid, relu are supported")

    return activation(z_curr), z_curr

  def forward(self, X):
    cache = {}
    A_current = X
    for layer_id_prev, layer in enumerate(self.architecture):
      current_layer_id = layer_id_prev+1

      A_previous = A_current
      activation = layer['activation']

      W_curr = self.params['W'+str(current_layer_id)]
      b_curr = self.params['b'+str(current_layer_id)]

      A_current, Z_curr = forward_prop_this_layer(A_previous, W_curr,
                                                  b_curr, activation)

      cache['A'+str(layer_id_prev)] = A_previous
      cache['Z'+str(current_layer_id)] = Z_curr

    return A_current, cache