mutating.rb

class OddPunisher
  def initialize(numbers)
    @numbers = numbers
    clean
  end
  
  def clean
    @numbers.delete_if { |n| n.to_i.even? }
  end
end

irb> numbers = [1, 2, 3, 4]
=> [1, 2, 3, 4]

irb> OddPunisher.new(numbers)
=> #<OddPunisher:0x007fe9eb1ae190 @numbers=[1, 3]>

irb> numbers
=> [1, 3]