package Coord;
use overload '+' => \&add;

sub new {
    my ($class, $x, $y) = @_;
    return bless { x => $x, y => $y}, $class;
}

sub add {
   my ($self, $other) = @_;
   return Coord->new($self->{x} + $other->{x}, 
       $self->{y} + $other->{y});
}