pub fn set_global_default<S>(subscriber: S) -> Result<(), SetGlobalDefaultError>where S: Subscriber + Send + Sync + 'static,
Sets this subscriber as the global default for the duration of the entire program.
Will be used as a fallback if no thread-local subscriber has been set in a thread (using
Can only be set once; subsequent attempts to set the global default will fail. Returns whether the initialization was successful.
Note: Libraries should NOT call
set_global_default()! That will cause conflicts when
executables try to set them later.