Add64 returns: 1) a + b 2) If there is overflow, an error.

Max64 returns the maximum of the values provided.

Min64 returns the minimum of the values provided.

Mul64 returns: 1) a * b 2) If there is overflow, an error.

Sub64 returns: 1) a - b 2) If there is underflow, an error.

Averager tracks a continuous time exponential moving average of the provided values.