Lwt logger for js_of_ocaml
log ?section ?logger ~level message logs a message.
exn is provided, then its string representation
Printexc.to_string exn) will be append to the message, and if
possible the backtrace will also be logged.
inspect is provided, it will be append to the message.
location contains the location of the logging directive, it is
of the form
(file_name, line, column).
The following functions are the same as log except that their name determines which level is used.
For example [root:info msg] is the same as [root:log ~level:Info msg].