Try to fix formatting of a code block

lib/Type/Promise.pod

@@ -27,10 +27,11 @@ The second is to create your promises yourself with C<Promise.new>. If you
 want to ensure that only your code can keep or break the promise, you can use
 the C<vow> method to get a unique handle, and call C<keep> or C<break> on it:
 
+=begin code
     sub async-get-with-promise($user-agent, $url) {
         my $p = Promise.new;
         my $v = $p.vow;
-    
+
         # do an asynchronous call on a fictive user agent,
         # and return the promise:
         $user-agent.async-get($url,
@@ -43,6 +44,7 @@ the C<vow> method to get a unique handle, and call C<keep> or C<break> on it:
         );
         return $p;
     }
+=end code
 
 =head1 Methods