Nil punting ruby

nil_class.rb

class NilClass
  include Enumerable

  def [](index)
    self
  end

  def merge(hash)
    hash.dup
  end

  def each
  end
end

array = nil
array.map { |a| a + 2 } # => []
array[4] # => nil
array.merge(:foo => :bar) # => {:foo => :bar}