code: def add_mark(self, mark_name):
      if mark_name not in self.marks:
          self._missing_marks.append(mark_name)
  
imports: import functools
  import importlib
  import inspect
  import json
  import os
  import subprocess
  import tempfile
  import types
  import warnings
  import pytest
  from matplotlib import pyplot
  import geomstats.backend
  from geomstats.exceptions import AutodiffNotImplementedError
  from geomstats.test.test_case import autodiff_backend
  from geomstats.test.vectorization import test_vectorization
label_desc: Use image node_id 7 for calling the TestFunction obj's underlying member method code with example usage: obj.add_mark(mark_name) without return types