whyyyyyyy?

gistfile1.rb

class Hash
  def [](k)
    fetch(k) do
      super[k.intern] || super[k.to_s]
    end
  end
end

{ key: 'EXPECTED'}['key']

NoMethodError: super: no superclass method `[]' for {:key=>"EXPECTED"}:Hash
  from /home/dlt/projects/programming/ruby/webapi/hash.rb:2:in `block in []'
  from /home/dlt/projects/programming/ruby/webapi/hash.rb:2:in `fetch'
  from /home/dlt/projects/programming/ruby/webapi/hash.rb:2:in `[]'
  from /home/dlt/projects/programming/ruby/webapi/hash.rb:4:in `<top (required)>'
  from (irb):1:in `load'
  from (irb):1
  from /home/dlt/.rvm/rubies/ruby-1.9.2-p290/bin/irb:16:in `<main`