Set default limit value

lib/random/random.js

@@ -12,22 +12,18 @@ class random {
    */
   static init (seed = new Date().getTime()) {
     random.twister = new MersenneTwister()
-    random.twister.seed(random.seed)
+    random.twister.seed(seed)
   }
 
   /**
    * Returns an integer in [0, limit) (uniform distribution)
    * @param {number} limit
    */
-  static number (limit) {
+  static number (limit = 0xffffffff) {
     if (!random.twister) {
       throw new Error('random.init must be called first.')
     }
 
-    if (limit === null || limit === undefined) {
-      limit = 0xffffffff
-    }
-
     let x = (0x100000000 / limit) >>> 0
     let y = (x * limit) >>> 0
     let r