In Backtrace§

See primary documentation in context for method outer-caller-idx

method outer-caller-idx(Backtrace:D: Int $startidx)

Returns as a list the index of the frames that called the current one.

sub zipi { { { die "Something bad happened" }() }() };
try zipi;
say $!.backtrace.outer-caller-idx4 ); # OUTPUT: «[6]␤»