code: def _default_resolver(self, network, func):
      self._functions.append(func)
      for i in func.input:
          self._referred.add(i)
      for o in func.output:
          self._referred.add(o)
  
file_path: nnabla/python/src/nnabla/utils/converter/nnablart/resolver.py
imports: from collections import OrderedDict
  import nnabla
  import nnabla.functions
  import numpy
  from nnabla.utils import nnabla_pb2
  from nnabla.utils.save_function import _create_function_nntxt
label_desc: Use image node_id 6 for calling the Resolver obj's underlying member method code with example usage: obj._default_resolver(network, func) without return types