code: def sample(self, mu):
          
          return np.random.wald(mean=mu, scale=self.scale, size=None)
docs: Return random samples from this Inverse Gaussian (Wald) distribution.
  
          Parameters
          ----------
          mu : array-like of shape n_samples or shape (n_simulations, n_samples)
              expected values
  
          Returns
          -------
          random_samples : np.array of same shape as mu