Run code after a subroutine call, preserving the context
Description
Sometimes you need to call a function, get the results, act on the results,
then return the result of the function. This is painful because of contexts;
the original function can behave different if it's called in void, scalar, or
list context. You can ignore the various cases and just pick one, but that's
fragile. To do things right, you need to see which case you're being called
in, and then call the function in that context. This results in 3 code paths,
which is a pain to type in (and maintain). This module automates the process.
You provide a code reference that is the "original function", and another code
reference to run after running the original. You can modify the return value
(aliased to @_) here, and do whatever else you need to do. 'wantarray' is
correct inside both code references; in "after", though, the return value is
ignored and the value 'wantarray' returns is related to the context that the
original function was called in.
