Documentation for postcircumfix « » assembled from the following pages:

Language documentation: Operators §

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(Operators) postcircumfix « » §

Shortcut for postcircumfix { } that quotes its argument using the same rules as the interpolating quote-words operator of the same name.

my %color = kiwi => "green", banana => "yellow", cherry => "red";
my $fruit = "kiwi";
say %color«cherry "$fruit"».raku;   # OUTPUT: «("red", "green")␤»

Technically, not a real operator; it's syntactic sugar that's turned into the { } postcircumfix operator at compile-time.