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multi sub unimatch(Str:D $str, |c)
multi sub unimatch(Int:D $code, Stringy:D $pvalname, Stringy:D $propname = $pvalname)

Checks if the given integer codepoint or the first letter of the given string has a unicode property equal to the value you give. If you supply the Unicode property to be checked it will only return True if that property matches the given value.

say unimatch 'A', 'Latin';           # OUTPUT: «True␤» 
say unimatch 'A', 'Latin', 'Script'; # OUTPUT: «True␤» 
say unimatch 'A', 'Ll';              # OUTPUT: «False␤»

The last property corresponds to "lowercase letter", which explains why it returns false.