def is_valid_reference(bookname, chapter, verse=None,
                                 end_chapter=None, end_verse=None):
    try:
        return normalize_reference(bookname, chapter, verse,
            end_chapter, end_verse) is not None
    except InvalidReferenceException:
        return False
Compute the predictive log likelihood
dataset/ETHPy150Open davisd/python-scriptures/scriptures/references.py/is_valid_reference--crossover with--dataset/ETHPy150Open slinderman/pyhawkes/experiments/synthetic_comparison.py/compute_predictive_ll