Add the parser to parse the string as an integer if it's needed.

src/cipher_analytical_machine/parsers/parsers.clj

@@ -3,7 +3,21 @@
   (:gen-class))
 
 (defn unsigned-int?
+  "Return true if the string is an unsigned integer."
   [str]
   (if (re-matches #"\d+" str)
     true false))
 
+(defn parse-unsigned-int
+  "Return an integer if the argument is an integer."
+  [str-or-int]
+  (cond
+    (int? str-or-int)
+    str-or-int
+
+    (unsigned-int? str-or-int)
+    (Integer/parseInt str-or-int)
+
+    :else
+    nil))
+