code: def get_input_nodes(self):
      return [node for node in self.nodes if len(node.parents) == 0]
  
imports: from collections import namedtuple
  from functools import reduce
  from google.protobuf import text_format
  from copy import deepcopy
  import numbers
  import os
  import tempfile
  from mmdnn.conversion.caffe.mapper import get_handler_name
  from mmdnn.conversion.caffe.resolver import get_caffe_resolver, has_pycaffe
  from mmdnn.conversion.caffe.shape import *
  from mmdnn.conversion.caffe.errors import print_stderr, ConversionError
label_desc: Use image node_id 4 for calling the CaffeGraph obj's underlying member method code with example usage: obj.get_input_nodes() and returns: unknown