Documentation for method subname assembled from the following pages:

Class: Backtrace::Frame §

From Backtrace::Frame

(Backtrace::Frame) method subname §

Defined as:

method subname(Backtrace::Frame:D --> Str)

Returns the name of the enclosing subroutine.

my $bt = Backtrace.new;
my $btf = $bt[0];
say $btf.subname;