code: def pdf(self, mu):
          
          if self.transform is not None:
              mu = self.transform(mu)             
          return (1.0/float(self.sigma0))*np.exp(-(0.5*(mu-self.mu0)**2)/float(self.sigma0**2))
docs: PDF for Normal prior
  
          Parameters
          ----------
          mu : float
              Latent variable for which the prior is being formed over
  
          Returns
          ----------
          - p(mu)