fix this: class flattenarray def self.flatten(ar) return [] if ar.all?(&:nil?) ar.compact! if ar.include?(nil) ar.flatten end end in ruby

To fix the code, you can make the following changes:

main.rb
class FlattenArray
  def self.flatten(ar)
    return [] if ar.nil?
    ar.flatten.compact
  end
end
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7 lines

Here are the changes made:

1. The class name flattenarray is changed to FlattenArray to follow Ruby conventions of using CamelCase for class names.
2. The return [] if ar.all?(&:nil?) statement is changed to return [] if ar.nil? to handle cases where the input array is nil.
3. The ar.compact! if ar.include?(nil) statement is removed because flatten already removes nil values.
4. The ar.flatten statement is moved to the end and combined with compact to first remove nil values and then flatten the array.
5. Proper indentation is added to improve code readability.

Now, the flatten method in the FlattenArray class will return a flattened array with nil values removed.