Yes, using custom tags. Example in Python, making the !join tag join strings in an array:

supports standard Markdown (with some minor modifications) and various extensions that have been made popular by the PHP Markdown Extra package and Maruku

The main difference is in the flow of how messages are ultimately sent to devices for output. The standard library Logger logic converts the log entries to strings and then sends the string to the device to be written to a stream. Lumberjack, on the other hand, sends structured data in the form of a Lumberjack::LogEntry to the device and lets the device worry about how to format it. The reason for this flip is to better support structured data logging. Devices (even ones that write to streams) can format the entire payload including non-string objects and tags however they need to.

The logging methods (debug, 'info', 'warn', 'error', 'fatal') are overloaded with an additional argument for setting tags on the log entry.