Perl module to get caller return OP address and Perl interpreter context

 Devel::Callsite module provides subroutines to get the caller return OP
 address and perl interpreter context.
 .
 The callsite() function returns the OP address of the caller, a number,
 one level up from where it was called. It's useful for functions that
 need to uniquely know where they were called, such as Every::every();
 see Every. Or it can be used to pinpoint a location with finer
 granularity than a line number (see
 http://www.perlmonks.com/?node_id=987268). In conjunction with an OP
 tree disassembly you can know exactly where the caller is located in
 the Perl source.
 .
 The context() function returns the interpreter context as a number.
 This is a fairly unique number together with the call site.