code: function findBookFromGroups (book) {
          if (book) {
            return book
          }
          var g
          for (let gu in selectedGroups) {
            g = kb.sym(gu)
            let b = kb.any(undefined, ns.vcard('includesGroup'), g)
            if (b) return b
          }
          throw new Error('findBookFromGroups: Cant find address book which this group is part of')
        }
docs: The book could be the main subject, or linked from a group we are dealing with