Plots the learning history for a Keras model,
    assuming the validation data was provided to the 'fit' function.

    Args:
        history: The return value from the 'fit' function.
        figsize: The size of the plot.

def plot_loss_history(history, figsize=(15, 8)):
    """
    Plots the learning history for a Keras model,
    assuming the validation data was provided to the 'fit' function.

    Args:
        history: The return value from the 'fit' function.
        figsize: The size of the plot.
    """

    plt.figure(figsize=figsize)

    plt.plot(history.history["loss"])
    plt.plot(history.history["val_loss"])

    plt.xlabel("# Epochs")
    plt.ylabel("Loss")
    plt.legend(["Training", "Validation"])
    plt.title("Loss over time")

    plt.show()