code: def test_get_parents(self):
      self.assertDictEqual(
          self.writer.get_parents(),
          {
              "asia": [],
              "bronc": ["smoke"],
              "dysp": ["bronc", "either"],
              "either": ["lung", "tub"],
              "lung": ["smoke"],
              "smoke": [],
              "tub": ["asia"],
              "xray": ["either"],
          },
      )
  
imports: import unittest
  import numpy
  from pgmpy import config
  from pgmpy.readwrite import NETReader, NETWriter
  from pgmpy.utils import compat_fns, get_example_model
label_desc: Use image node_id 4 for calling the TestNETWriter obj's underlying member method code with example usage: obj.test_get_parents() without return types