# File lib/mongo/util/read_preference.rb, line 76
    def select_near_pool(candidates, latency)
      nearest_pool = candidates.min_by { |candidate| candidate.ping_time }
      near_pools = candidates.select do |candidate|
        (candidate.ping_time - nearest_pool.ping_time) <= latency
      end
      near_pools[ rand(near_pools.length) ]
    end