output.txt

~ % ruby hash.rb 
"foo"
nil
hash.rb:9:in `[]': PythonLike (PythonLike)
        from hash.rb:14

pythonify.rb

hash = {:python => 'foo', :perl => 'bar', :ruby => 'spam'}
puts hash[:python].inspect
puts hash[:php].inspect

class PythonLike < Exception; end

class Hash
  def [](key)
    raise PythonLike unless self.has_key?(key)
    super
  end
end

puts hash[:java].inspect