README.md in digest-stringbuffer-0.0.2 vs README.md in digest-stringbuffer-0.0.3

@@ -12,11 +12,11 @@
 
 Digest::StringBuffer depends only one method `finish`.
 
 ```ruby
 module Digest
-  class Prime31
+  class Prime31 < StringBuffer
     def initialize
       @prime = 31
     end
   
     def finish
@@ -27,10 +27,10 @@
       [result & 0xffffffff].pack("N")
     end
   end
 end
 
-p Digest::Prime.hexdigest("abc" * 1000) #=> "008b1190"
+p Digest::Prime31.hexdigest("abc" * 1000) #=> "008b1190"
 ```
 
 ## APIs
 
 ### Class methods