Changing class and using the Each Method

changeClass.rb

class Array
  def sum_numbers
    sum = 0
    self.each { |num| sum += num }
    sum
  end
  
  def add_index
    self.each_with_index do |item, index|
        self[index] = "#{index} is #{item}"
    end
  end
    
end

class String
  def camel_case
    words = self.split
    words.each {|word| word.capitalize! }
    words[0].downcase!
    words.join
  end
end