Function slog_env_cfg::drain_from_env

pub fn drain_from_env(
) -> Result<impl SendSyncRefUnwindSafeDrain<Ok = (), Err = Never>, ConfigFromEnvError>

Build slog Drain (more specificly SendSyncRefUnwindSafeDrain) using the config obtained from env. The resulting Drain is ready to be passed to the slog::Logger::root.