o.rb

[1] pry(main)> class A
[1] pry(main)*   def x
[1] pry(main)*     puts "from A"
[1] pry(main)*   end
[1] pry(main)* end
=> :x
[2] pry(main)> class B < A
[2] pry(main)*   def x
[2] pry(main)*     puts "from B"
[2] pry(main)*   end
[2] pry(main)* end
=> :x
[3] pry(main)> class C < B
[3] pry(main)*   def x
[3] pry(main)*     puts "from C"
[3] pry(main)*   end
[3] pry(main)* end
=> :x
[4] pry(main)> C.new.x
from C
=> nil
[5] pry(main)> C.new.method(:x).super_method.call
from B
=> nil
[6] pry(main)> C.new.method(:x).super_method.super_method.call
from A
=> nil
[7] pry(main)>