It's best to define respond_to_missing instead of respond_to?

README.md

@@ -1389,7 +1389,7 @@ patch them.)
     ```
 
 * avoid using `method_missing` for metaprogramming. Backtraces become messy; the behavior is not listed in `#methods`; misspelled method calls might silently work (`nukes.launch_state = false`). Consider using delegation, proxy, or `define_method` instead.  If you must, use `method_missing`,
-  - be sure to [also define `respond_to?`](http://devblog.avdi.org/2011/12/07/defining-method_missing-and-respond_to-at-the-same-time/)
+  - be sure to [also define `respond_to_missing?`](http://blog.marc-andre.ca/2010/11/methodmissing-politely.html)
   - only catch methods with a well-defined prefix, such as `find_by_*` -- make your code as assertive as possible.
   - call `super` at the end of your statement
   - delegate to assertive, non-magical methods: