my_flatten.rb

def flatten(integer_array)
  result = []
  integer_array.each do |i|
    if i.is_a? Array
      # It's and array.  Go a recursevely flatten this child element
      child_array = flatten i
      result.concat child_array
    else
      # It's an integer.  Just added to the final array
      result << i
    end
  end
  result
end