try except unnecessary step

Question

Is it always safe to use hello2 instead of hello1 ?

def hello1():
    try:
        aaa = foo()
        return aaa
    except baz:
        return None   

def hello2():
    try:
        return foo()
    except baz:
        return None   

Answer 1

Yes, it is.

Assigning first then returning makes no difference when it comes to catching exceptions. The assignment to aaa is entirely redundant.

Answer 2

Yes, it makes no difference at all. Your possible source of an exception is the foo() function and you call it anyway in both programs. Assigning its output to aaa will not change anything, since the exception will originate when calling foo() not during the assignment (which is located in try block anyway).