source: [lemma=□] □
destination: [lemma=we] □
spec: One key goal is to support rich enough descriptions of how a service works that we can derive facts about what it does , how much it would cost and other features of the service . It must be acknowledged , however , that the possibility of adverse effects , such as psychological and physical morbidity related to the syndrome of protracted abstinence or the potential for psychological distress driven by a fear of withdrawal , has not been investigated .