code: def config_string(self, layer_to_string):
      if self.operator is None:
          assert len(self.items) == 1 and isinstance(self.items[0], str)
          return layer_to_string(self.items[0])
      else:
          assert isinstance(self.operator, str)
          return (
              self.operator
              + "("
              + ", ".join(
                  [
                      item.config_string(layer_to_string)
                      if isinstance(item, Descriptor)
                      else str(item)
                      for item in self.items
                  ]
              )
              + ")"
          )
  
imports: from __future__ import print_function
  from __future__ import division
  import re
  import sys
label_desc: Use image node_id 2 for calling the Descriptor obj's underlying member method code with example usage: obj.config_string(layer_to_string) and returns: layer_to_string, unknown