def values(from, to)
      values = connection.metric_values(@id, from, to)
      values.map { |row| row.first.to_i }
    end
def values(from, to)
      values = connection.metric_values(@id, from, to)
      values.map { |row| row.first.to_i }
    end
Given two arguments, a start date and an end date (inclusive), returns an
 array of measurements. All metrics must implement this method.