Calculates accuracy using :class:`~ignite.metrics.ConfusionMatrix` metric.
    Args:
        cm (ConfusionMatrix): instance of confusion matrix metric

    Returns:
        MetricsLambda

def cmAccuracy(cm):
    """
    Calculates accuracy using :class:`~ignite.metrics.ConfusionMatrix` metric.
    Args:
        cm (ConfusionMatrix): instance of confusion matrix metric

    Returns:
        MetricsLambda
    """
    # Increase floating point precision
    cm = cm.type(torch.float64)
    return cm.diag().sum() / (cm.sum() + 1e-15)