Format builder's state as RUST_LOG-like value

[nyurik]

For logging purposes, I would like to print the RUST_LOG and possibly RUST_LOG_STYLE values as ingested by the env_logger. Is there a way to serialize internal state of the env_logger::Builder as a RUST_LOG-like string?

I could of course just read the RUST_LOG env var, and do a default fallback, but it seems this won't be as clean as having the builder format its own state?