def add_series(series)
      raise ArgumentError, "Invalid argument 'series'. Expected Series, got #{series.class}." unless series.is_a?(Series)
      # Do not add it again if the series already belongs to this instance:
      @series << series unless @associated_series[series.uid]
      @image_series << series if series.is_a?(ImageSeries) && !@associated_series[series.uid]
      @associated_series[series.uid] = series
      @associated_iseries[series.uid] = series if series.is_a?(ImageSeries)
    end
def add_series(series)
      raise ArgumentError, "Invalid argument 'series'. Expected Series, got #{series.class}." unless series.is_a?(Series)
      # Do not add it again if the series already belongs to this instance:
      @series << series unless @associated_series[series.uid]
      @image_series << series if series.is_a?(ImageSeries) && !@associated_series[series.uid]
      @associated_series[series.uid] = series
      @associated_iseries[series.uid] = series if series.is_a?(ImageSeries)
    end
Adds a Series to this Study.

 @param [Series] series a series instance to be associated with this study