caller
caller - get context of the current subroutine call
caller EXPR
caller
Returns the context of the current subroutine call.  In a scalar context,
returns TRUE if there is a caller, that is, if we're in a subroutine or
eval()
 or 
require()
, and FALSE otherwise.  In a list context, returns
    ($package, $filename, $line) = caller;
With EXPR, it returns some extra information that the debugger uses to
print a stack trace.  The value of EXPR indicates how many call frames
to go back before the current one.
    ($package, $filename, $line,
     $subroutine, $hasargs, $wantargs) = caller($i);
Furthermore, when called from within the DB package, caller returns more
detailed information: it sets the list variable @DB::args to be the
arguments with which that subroutine was invoked.