Nested functions exception handling

Original question asked in Real Python slack group:
I have a question about chained exception handling method and how to return except conditions when I use it for one function which relies on another function. The code can be found below for more context: It looks to me from answers I got from experienced folks in Real python, there are two ways to do this:
In main function write try/except code and raise the exception from nested inner function Hello this is my rewriten code which required a custom class in Python: py class ModelNotSupported(Exception): pass
supported = ["a", "b", "c", "en", "ta"]
def load_model(source, target):
if source == target:
raise ModelNotSupported("Hello how are you")
if source in supported:
if source == "en":
return ("t", "t")
raise ModelNotSupported("Language pair not available")
def predict_raw():
tokenizer, model = load_model("en", "hello")
return model
except ModelNotSupported as e:
return {"inputerror": e}
This can be be implemented with a function which returns messages, and based on which return based on the conditions.