```ruby
module TicketEvolution
  class Collection
    attr_accessor :total_entries, :per_page, :current_page, :entries, :status_code, :unique_categories

    include Enumerable

    delegate :each, :last, :size, :[], :to => :entries
    alias :all :entries
    alias :code :status_code

    def initialize(options = {})
      options.each {|k,v| send("#{k}=", v)}
      @entries ||= []
    end

    def self.build_from_response(response, entries_key, singular_class)
      entries = response.body[entries_key] || []
      values = {
        :status_code => response.response_code,
        :total_entries => response.body['total_entries'],
        :per_page => response.body['per_page'],
        :current_page => response.body['current_page'],
        :entries => entries.collect do |entry|
          singular_class.new(entry.merge({:connection => response.body[:connection]}))
        end
      }
      values[:unique_categories] = response.body['unique_categories'] if response.body['unique_categories']
      new(values)
    end
  end
end
```

Add handling for possible total_sum and balance_sum list values
user
```ruby
module TicketEvolution
  class Collection
    attr_accessor :total_entries, :per_page, :current_page, :entries, :status_code, 
                  :unique_categories, :balance_sum, :total_sum

    include Enumerable

    delegate :each, :last, :size, :[], :to => :entries
    alias :all :entries
    alias :code :status_code

    def initialize(options = {})
      options.each {|k,v| send("#{k}=", v)}
      @entries ||= []
    end

    def self.build_from_response(response, entries_key, singular_class)
      entries = response.body[entries_key] || []
      values = {
        :status_code => response.response_code,
        :total_entries => response.body['total_entries'],
        :per_page => response.body['per_page'],
        :current_page => response.body['current_page'],
        :entries => entries.collect do |entry|
          singular_class.new(entry.merge({:connection => response.body[:connection]}))
        end
      }
      values[:unique_categories] = response.body['unique_categories'] if response.body['unique_categories']
      values[:balance_sum] = response.body['balance_sum'] if response.body['balance_sum']
      values[:total_sum] = response.body['total_sum'] if response.body['total_sum']
      new(values)
    end
  end
end
```
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