Array flatten

flatten.rb

# Transform a possible multi-dementional array into one-dimentional array
# It returns nil if the giver argument is not an array
def flatten(arr)
  return nil unless arr.is_a?(::Array)

  # Store the extracted values in the result
  result = []

  # Iterate over the elements appending or merging the parts
  arr.each do |part|
    if part.is_a?(::Array)
      result.concat(flatten(part))
    else
      result << part
    end
  end

  # Return the result
  result
end