internal DbConstraint ExtendBySubject(DbConstraint subject, string question)
{
var newEntry = new ConstraintEntry(subject, question, null);
return(new DbConstraint(PhraseConstraint, _entries.Concat(new[] { newEntry }).ToArray()));
}
internal DbConstraint ExtendByAnswer(string question, DbConstraint answer)
{
var newEntry = new ConstraintEntry(null, question, answer);
return(new DbConstraint(PhraseConstraint, _entries.Concat(new[] { newEntry }).ToArray()));
}