text: import numpy as np
  from ..layers import Layer
  
  class TanH(Layer):
      '''
      '''
      def forward(self, x):
          self.last_x = x
          self.result = (np.exp(x) - np.exp(-x))/(np.exp(x) + np.exp(-x))
          return self.result
  
      def __call__(self, x):
          return self.forward(x)
  
      def backward(self, dL_dy):
          self.dy_dx = 1 - self.result**2
          return self.dy_dx * dL_dy
  
  class tanh(TanH):
      def __init__(self):
          pass
  