code: def build_extensions(self):
      from sklearn._build_utils.openmp_helpers import get_openmp_flag
  
      # Always use NumPy 1.7 C API for all compiled extensions.
      # See: https://numpy.org/doc/stable/reference/c-api/deprecations.html
      DEFINE_MACRO_NUMPY_C_API = (
          "NPY_NO_DEPRECATED_API",
          "NPY_1_7_API_VERSION",
      )
      for ext in self.extensions:
          ext.define_macros.append(DEFINE_MACRO_NUMPY_C_API)
  
      if sklearn._OPENMP_SUPPORTED:
          openmp_flag = get_openmp_flag()
  
          for e in self.extensions:
              e.extra_compile_args += openmp_flag
              e.extra_link_args += openmp_flag
  
      build_ext.build_extensions(self)
  
imports: import importlib
  import os
  import platform
  import shutil
  import sys
  import traceback
  from os.path import join
  from setuptools import Command, Extension, setup
  from setuptools.command.build_ext import build_ext
  import sklearn
  import sklearn._min_dependencies
  from sklearn._build_utils import _check_cython_version
  from sklearn.externals._packaging.version import parse
label_desc: Use image node_id 2 for calling the build_ext_subclass obj's underlying member method code with example usage: obj.build_extensions() without return types