sub FETCH {
  my ($self, $key) = @_;
  my $is_re = (ref($key) eq 'Regexp');

  return $self->{$key} if !$is_re and exists $self->{$key};
  $key = qr/$key/ if !$is_re;

  if (wantarray) {
    return @{$self}{ grep /$key/, keys %$self };
  }
  else {
    /$key/ and return $self->{$_} for keys %$self;
  }
}