D语言发布条件的块

import std.stdio;
import std.string;

double getAge(double months,double years) 
in { 
   assert(months >= 0); 
   assert(months <= 12); 
}

out (result) { 
   assert(result>=years); 
} 

body { 
   return years + months/12; 
} 

void main () { 
   writeln(getAge(10,12)); 
}