Merge pull request matplotlib#19041 from anntzer/eh

Reword docs for exception_handler in CallbackRegistry.

Author: QuLogic

lib/matplotlib/cbook/__init__.py

@@ -138,20 +138,14 @@ class CallbackRegistry:
     Parameters
     ----------
     exception_handler : callable, optional
-       If provided must have signature ::
-
-          def handler(exc: Exception) -> None:
-
-       If not None this function will be called with any `Exception`
-       subclass raised by the callbacks in `CallbackRegistry.process`.
-       The handler may either consume the exception or re-raise.
-
-       The callable must be pickle-able.
-
-       The default handler is ::
-
-          def h(exc):
-              traceback.print_exc()
+       If not None, *exception_handler* must be a function that takes an
+       `Exception` as single parameter.  It gets called with any `Exception`
+       raised by the callbacks during `CallbackRegistry.process`, and may
+       either re-raise the exception or handle it in another manner.
+
+       The default handler prints the exception (with `traceback.print_exc`) if
+       an interactive event loop is running; it re-raises the exception if no
+       interactive event loop is running.
     """
 
     # We maintain two mappings: