+ import std.math;
  import std.typecons;
- import std.math;
  /*
   Find the shortest palindrome that begins with a supplied string.
-     Algorithm idea is simple:
? ----

+ Algorithm idea is simple:
-     - Find the longest postfix of supplied string that is a palindrome.
? ----

+ - Find the longest postfix of supplied string that is a palindrome.
-     - Append to the end of the string reverse of a string prefix that comes before the palindromic suffix.
? ----

+ - Append to the end of the string reverse of a string prefix that comes before the palindromic suffix.
-     >>> make_palindrome("")
? ----

+ >>> make_palindrome("")
-     ""
+ ""
-     >>> make_palindrome("cat")
? ----

+ >>> make_palindrome("cat")
-     "catac"
? ----

+ "catac"
-     >>> make_palindrome("cata")
? ----

+ >>> make_palindrome("cata")
-     "catac"
? ----

+ "catac"
-     
  */
  string make_palindrome(string string)