NewCounters creates a new counter vec.

NewGauges creates a new gauge vec.

NewHistograms creates a new histogram vec.

Counters is a vec tor of counters for a each log stream.

Gauges is a vector of gauges for a each log stream.

Histograms is a vector of histograms for a each log stream.

Expirable allows checking if something has exceeded the provided maxAge based on the provided currentTime.