It is harder to understand a function if, reading it at the bottom, you are unaware of the possibility that it returned somewhere above. So multiple returns in a function should be avoided, if possible. However, in some situations it is perfectly legal to have extra returns. Examples are:

• precondition checks that fail at the beginning of a function
• loops that should terminate as soon as some condition is met (e.g. return the first element larger than 10 in a list)