pub fn log_error( level: Level, target: &str, e: &AnyError, format: ErrorLogFormat)
Log one error on given log level.
It is printed to the log with all the causes and optionally a backtrace (if it is available and
debug logging is enabled).
This is the low-level version with full customization. You might also be interested in
log_errors or one of the convenience macro (log_error).