code: def stableSlugId():
      
      _cache = {}
  
      def closure(name):
          if name not in _cache:
              _cache[name] = slugId()
          return _cache[name]
  
      return closure
docs: Returns a closure which can be used to generate stable slugIds.
      Stable slugIds can be used in a graph to specify task IDs in multiple
      places without regenerating them, e.g. taskId, requires, etc.