package Boundary;
    use strictures 2;
    use namespace::clean;
    use Data::Dumper;
    use Moo;
    use MooX::Types::MooseLike::Base qw/ HashRef Int Maybe /;
    with q{MooX::Singleton};

    has q{limit} => (
        is => q{rw},
        isa => HashRef [ HashRef [ Maybe [Int] ] ],
        traits => [ q{Hash}, ],
        default => sub { {} },
    );