class Object
def acts_like?(duck)
"x.acts_like?(:date)" to do duck-type-safe comparisons, since classes that
acts_like_time?. As a result, we can do "x.acts_like?(:time)" and
to define an acts_like_date? method, and extends Time to define
A duck-type assistant method. For example, Active Support extends Date
def acts_like?(duck) respond_to? :"acts_like_#{duck}?" end