What's wrong with these candidates?

gistfile1.txt

proto sub slurp(|) {*}
multi sub slurp(*%_) { $*ARGFILES.slurp(|%_) }
multi sub slurp(IO::Handle:D $fh, *%_) {   $fh.slurp(|%_) }
multi sub slurp(IO()       $path, *%_) { $path.slurp(|%_) }

proto sub spurt($, $, |) {*}
multi sub spurt(IO::Handle:D $fh, $data, *%_) {   $fh.spurt($data, |%_) }
multi sub spurt(IO()       $path, $data, *%_) { $path.spurt($data, |%_) }