Base Hazard Functions

Base hazard functions.

Exponential(lmda, *[, frozen])	Implements the Exponential base hazard.
Gompertz(a, b, *[, clock_type, frozen])	Implements the Gompertz base hazard.
LogNormal(mu, scale, *[, clock_type, frozen])	Implements the log normal base hazard.
Weibull(lmda, k, *[, clock_type, frozen])	Implements the Weibull base hazard.