code: def testDocstringModulesAreValidModules(self):
      for _, docsrc in doc_srcs.get_doc_sources(FLAGS.api_name).items():
          if docsrc.docstring_module_name:
              doc_module_name = ".".join(
                  [FLAGS.package, docsrc.docstring_module_name]
              )
              self.assertIn(
                  doc_module_name,
                  sys.modules,
                  msg=(
                      "docsources_module %s is not a valid module under %s."
                      % (docsrc.docstring_module_name, FLAGS.package)
                  ),
              )
  
file_path: tensorflow/tensorflow/python/tools/api/generator/doc_srcs_test.py
imports: import argparse
  import importlib
  import sys
  from tensorflow.python.platform import test
  from tensorflow.python.tools.api.generator import doc_srcs
label_desc: Use image node_id 3 for calling the DocSrcsTest obj's underlying member method code with example usage: obj.testDocstringModulesAreValidModules() without return types