re dimension of joint latent representation.
  n_epochs:     maximal epoch used in training.
  lambda_regul: weight for regularization term in the loss function.
  lambda_super: weight for supervised learning loss in the loss function.


Outputs:

  z:            joint latent representation learned by MUSE.
  x_hat:        reconstructed feature matrix corresponding to input data_x.
  y_hat:        reconstructed feature matrix corresponding to input data_y.
  h_x:          modality-specific latent representa