from gatel0rd import GateL0RD
#...
model = GateL0RD(input_size=input_dim, output_size=output_dim, hidden_size=args.latent_dim, reg_lambda=args.lambda)
optimizer = optim.Adam(model.parameters(), lr=args.lr) # optimizer of your choice
# ...
for X,Y in training_data:
    Y_hat, H, Theta = model.forward(X)
    optimizer.zero_grad()
    loss_task = F.mse_loss(Y_hat, Y) # loss of your choice
    loss = model.loss(loss_task, Theta)
    loss.backward()
    optimizer.step()
#...