Prior to 2.1, if you defined a method, you received nil
as a return value:
irb(main):001:0> def fun
irb(main):002:1> end
=> nil
With 2.1, the method definition returns a symbol for the method name:
irb(main):001:0> def fun
irb(main):002:1> end
=> :fun
One impact of this is that the following pattern for declaring a single private method
def fun
end
private :fun
can become:
private def fun
end
Now to decide if I like how that looks.