def get_smoothed_value(name: str, key: str) -> float:
    """Get a single smoothed value.

    Raises:
        KeyError: if no metrics have been logged under *name* and *key*.
    """
    return _aggregators[name].get_smoothed_value(key)
Get a single smoothed value.

Raises:
KeyError: if no metrics have been logged under *name* and *key*.
fairseq/logging/metrics.py