use Sub::Lexical;

sub find_key_dupes {
  my $binary_tree=shift;
  my $key=shift;
  my @dupes;

  my sub get_dupes($) {
    my $node=shift;
    return unless $node;
    if ($node->{key} lt $key) {
      get_dupes($node->{right});
    } else {
      push @dupes,$node if $node->{key} eq $key;
      get_dupes($node->{left});
    }
  }

  get_dupes($binary_tree);
  return \@dupes;
}