module for lexically scoped subroutine wrappers

 Hook::LexWrap allows you to install a pre- or post-wrapper (or both)
 around an existing subroutine. Unlike other modules that provide this
 capacity (e.g. Hook::PreAndPost and Hook::WrapSub), Hook::LexWrap
 implements wrappers in such a way that the standard caller function
 works correctly within the wrapped subroutine.