Documentation for method is-routine assembled from the following pages:

Class: Backtrace::Frame §

From Backtrace::Frame

(Backtrace::Frame) method is-routine §

Defined as:

method is-routine(Backtrace::Frame:D: --> Bool:D)

Return True if the frame points into a routine (and not into a mere Block).

my $bt = Backtrace.new;
my $btf = $bt[0];
say $btf.is-routine;