code: def get_thumbprint(self):
          
          d = {}
          if self.names:
              names = self.names
          else:
              names = list(self.satchel.lenv)
          for name in self.names:
              d[name] = deepcopy(self.satchel.env[name])
          return d
docs: Calculates the current thumbprint of the item being tracked.