In Quoting constructs§

See primary documentation in context for Interpolation: qq

my $color = 'blue';
say "My favorite color is $color!"# OUTPUT: «My favorite color is blue!␤» 

The qq form – usually written using double quotes – allows for interpolation of backslash escape sequences (like q:backslash), all sigiled variables (like q:scalar:array:hash:function), and any code inside {...} (like q:closure).