code: def get_parent(self):
          
          if not self.has_cached_parent:
              if self.parent is not None:
                  self._parent_block = self.runtime.get_block(self.parent)
              else:
                  self._parent_block = None
              self._parent_block_id = self.parent
          return self._parent_block
docs: Return the parent block of this block, or None if there isn't one.