Flatten example

Flatten.rb

data_array = [[1,2,[3]],4]

def manual_flatten(arr)
  new_array = []
  arr.each do |elm|
    if elm.kind_of?(Array)
      new_array.concat(manual_flatten(elm))
    else
      new_array << elm
    end
  end
  new_array
end

p manual_flatten(data_array)