package Foo;
sub foo : lvalue {
  my $self = shift;
  warn "Only first argument to method foo is used" if @_ > 1;
  $self->{ foo } = shift if @_;
  $self->{ foo };
}

my $x = bless +{}, 'Foo';
$x->foo = 3;
print $x->foo, "\n";
$x->foo++;
print $x->foo, "\n";
$x->foo += 6;
print $x->foo, "\n";

__END__
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