Ruby is object-oriented, modelled after Smalltalk mostly. So

irb(main):001:0> 10.class
=> Integer

So you'll just have implement the method "years" on the Integer (or something more generic like Numeric) class and then "ago" on whatever class the years method returned.

You might imagine that you can do something like 10.years().ago() in python but the parser prevents you:

>>> 10.years
  File "<python-input-0>", line 1
    10.years
      ^
SyntaxError: invalid decimal literal

Doesn't seem like it would have to prevent it, back in ruby:

irb(main):001:0> 10.0.class
=> Float

Ruby is a pretty cute language in my opinion, and I find it sad that python kinda drove over it.