custom_flatten.md

class FlatArray
  attr_reader :nested_array, :result

  def initialize(nested_array = [])
    @nested_array = nested_array
    @result = []
  end

  def call
    flat(nested_array)
    
    result
  end

  private

  def flat(nested_array)
    nested_array.each do |element|
      element.is_a?(Array) ? flat(element) : @result << element
    end
  end
end