TCOT base comain class

Story.cs

public abstract class Story : AggregateBase
{
    private readonly ISet<Vote> _votes = new HashSet<Vote>();
    private readonly ISet<Commentary> _comments = new HashSet<Commentary>();
    private readonly ISet<Relevancy> _relevancies = new HashSet<Relevancy>();

    protected Story()
    { }

    public virtual Relevancy Relate(Story story, User contributor, RelevancyScore score)
    {
        // construct relevancy
        var relevancy = RelevancyFactory.Create(this, story, contributor, score);
        
        // tally relevancy against story
        _relevancies.Add(relevancy);

        // pass vote back to client
        return relevancy;
    }

    public virtual Vote Vote(User contributor, VoteScore score)
    {
        // construct vote
        var vote = VoteFactory.Create(this, contributor, score);
            
        // tally vote against story
        _votes.Add(vote);

        // pass vote back to client
        return vote;
    }

    public virtual Commentary Comment(User contributor, CommentaryDetail detail)
    {
        // construct comment
        var comment = CommentaryFactory.Create(this, contributor, detail);
            
        // tally comment against story
        _comments.Add(comment);

        // pass comment back to client
        return comment;
    }
}