%rules = (
 _default => sub {
  if (scalar(keys %{$_[1]}) == 1) {
   return $_[0] => $_[1]->{_content}
  } else {
   return $_[0] => $_[1]
  }
 },
 phone => sub {$_[1]->{type} => $_[1]->{content}},
 phones => sub {delete $_[1]->{_content}; 'phones' => $_[1]}, 
);