array_flatten.rb

@flattened_array = [] #To store the flattened array
def flatten(array)
  array.each do |value|
    # If value is itself an array, call the function recursively
    # Store each value found that is not array in the flattened array
    value.instance_of? Array ? flatten value : @flattened_array << value
  end
  @flattened_array
end

#Usage
#flatten [1, 4,  6, [1, 2], [[5, 23], [44, 34, [23, 1]]]]
#  => [1, 4, 6, 1, 2, 5, 23, 44, 34, 23, 1]