gistfile1.rb

>> class Foo
>>   def bar
>>     puts 'in bar'
>>     end
>>   end
=> nil
>> class Foo2 < Foo
>>   def bar
>>     super
>>     puts 'in bar in foo2'
>>     end
>>   end
=> nil
>> f = Foo.new
=> #<Foo:0x007fc85110c068>
>> f.bar
in bar
=> nil
>> f2 = Foo2.new
=> #<Foo2:0x007fc8511026a8>
>> f.bar
in bar
=> nil
>> f2.bar
in bar
in bar in foo2
=> nil
>>