class Gladys::TimeSeries::Counter

def between(start:, finish:)
  return @values.values if start.nil? || finish.nil?
  start = start.utc.to_i
  finish = finish.utc.to_i
  result = {}
  (start...finish).map do |time|
    result[time - start] = 0
  end
  @values.each do |key, value|
    result[key - start] += value if result[key - start]
  end
  result
end