def plot_lc(d):
    """plot learning curve

    Arguments:
    d       Returned by model function. Dictionary containing information about the model.
    """
    costs = np.squeeze(d['costs'])
    plt.plot(costs)
    plt.ylabel('cost')
    plt.xlabel('iterations (per hundreds)')
    plt.title("Learning rate =" + str(d["learning_rate"]))
    plt.show()