NewMetric returns a new empty metric of dimension len(keys).

Gauge is a Kind that can take on any value, and may be set discontinuously from its previous value.

Timer is a specialisation of Gauge that can be used to store time intervals, such as latency and durations.

LabelSet is an object that maps the keys of a Metric to the labels naming a Datum, for use when enumerating Datums from a Metric.

LabelValue is an object that names a Datum value with a list of label strings.

Metric is an object that describes a metric, with its name, the creator and owner program name, its Kind, a sequence of Keys that may be used to add dimension to the metric, and a list of LabelValues that contain data for labels in each dimension of the Keys.

Store contains Metrics.

Kind enumerates the types of metrics supported.