code: def get_deletion_score(source_counts, prediction_counts, target_counts, beta=0):
    
    source_not_prediction_counts = source_counts - prediction_counts
    source_not_target_counts = source_counts - target_counts
    true_positives = sum((source_not_prediction_counts &
                          source_not_target_counts).values())
    selected = sum(source_not_prediction_counts.values())
    relevant = sum(source_not_target_counts.values())
    return _get_fbeta_score(true_positives, selected, relevant, beta=beta)
docs: Compute the deletion score (Equation 6 in the paper).