Erlang嵌套if语句

-module(helloworld). 
-export([start/0]). 

start() -> 
   A = 4, 
   B = 6, 
   if 
      A < B ->

         if 
            A > 5 -> 
               io:fwrite(A is greater than 5); 
            true -> 
               io:fwrite(A is less than 5)
         end;
      true -> 
         io:fwrite(A is greater than B) 
   end.