code: def _can_compute(self, _id, persistence):
          
          if self.store and self._stored(_id, persistence):
              return True
  
          if self.is_root:
              return False
  
          return all(
              [n._can_compute(_id, persistence) for n in self.dependencies])
docs: Return true if this feature stored, or is unstored, but can be computed
          from stored dependencies