import torch


def get_optimizer(lr):
    """
    Specify an optimizer and its parameters.

    Returns
    -------
    tuple(torch.optim.Optimizer, dict)
        The optimizer class and the dictionary of kwargs that should
        be passed in to the optimizer constructor.

    """
    return (torch.optim.SGD,
            {"lr": lr, "weight_decay": 1e-6, "momentum": 0.9})