Function refuses_presence 

pub fn refuses_presence<E: ConditionEvaluator + ?Sized>(
    status: &str,
    evaluator: &E,
    ctx: &EvaluationContext<'_>,
    ub_definitions: &BTreeMap<String, ConditionExpr>,
) -> bool

Whether something present under status is not allowed where ctx is: a Muss/X status with a condition that evaluates to false through PresentTarget. Soll/Kann, an unconditional status, an undecidable condition, a package ([19P1..1], judged by its own check) and a status of several lines refuse nothing.