Find an existing ArticleSeries for the given procedure reference, or create a new one and add it to the index.
Note: This function mutates index.series for convenience. Callers that require immutability should replace the series array after calling this.
index.series
Intelligence index to search / mutate
EP procedure reference (e.g. "2024/0001(COD)")
Display name for the series if it needs to be created
The found or newly created series
Find an existing ArticleSeries for the given procedure reference, or create a new one and add it to the index.
Note: This function mutates
index.seriesfor convenience. Callers that require immutability should replace the series array after calling this.