`val level : easy_lev Stdlib.ref`

Set this ref to the lowest level of log you want logged. For example, `Easy.level := `always` disables all logging except that at the ``always` level. Setting `Easy.level := `info` will enable logging for ``info`, ``warn`, ``error`, ``fatal` and ``always` levels.

`val output : unit BatIO.output Stdlib.ref`

Set this ref to the output you want logging messages to go to. Defaults to `stderr`.

`val log : ?fp:string -> easy_lev -> string -> unit`

`log lev msg` logs the message `msg` if the current logging level is `lev` or lower.

`val logf : ?fp:string -> easy_lev -> ('a, unit BatIO.output, unit) Stdlib.format -> 'a`

As `log`, but instead of a string message, a printf format is allowed with whatever arguments are appropriate.