gistfile1.txt

multi sub infix:<+>(Unit $x, Unit $y) {
    if (not $x.isSameUnit($y)) {die "Units do not match.";}
    return Unit.new(magnitude => $x.magnitude + $y.magnitude, units => $x.units);
}

my $a = Units::Unit.new(magnitude => 1.2, units => ("m" => 1));
my $b = Units::Unit.new(magnitude => 5.0, units => ("m" => 1));

say $a + $b;

ERROR: 
Cannot call Numeric(Units::Unit: ); none of these signatures match:
    (Mu:U \v: *%_)
  in block <unit> at t/units.t line 12