Flatten Array with using inbuilt method

flat_it

class Array #class so that this method is available for array. monkey patching 
  def flat_it
    each_with_object([]) do |element, flattened| #traverse each element
      flattened.push *(element.is_a?(Array) ? element.flat_it : element) #call method if Array, push to flattened if not array
    end
  end
end

#usage
[1,2,3,4,[1,2,3,4,[1,2,[44,34]]],5].flat_it
#output
#[1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 44, 34, 5]