Documentation for trait is raw assembled from the following types:

class Routine

From Routine

(Routine) trait is raw

Defined as:

multi sub trait_mod:<is>(Routine:D $r, :$raw!)

Gives total access to the data structure returned by the routine.

my @zipi = <zape zapatilla>;
sub þor() is raw {
    return @zipi
};
þor()[1] = 'pantuflo';
say @zipi;  # OUTPUT: «[zape pantuflo]␤»