class Rcov::CallSiteAnalyzer

def aggregate_data(aggregated_data, delta)
  callsites1, defsites1 = aggregated_data
  callsites2, defsites2 = delta

  callsites2.each_pair do |(klass, method), hash|
    dest_hash = (callsites1[[klass, method]] ||= {})
    hash.each_pair do |callsite, count|
      dest_hash[callsite] ||= 0
      dest_hash[callsite] += count
    end
  end
  defsites1.update(defsites2)
end