code: def build_extensions(self):
      if (
          self.parallel is None
          and os.environ.get("SPACY_NUM_BUILD_JOBS") is not None
      ):
          self.parallel = int(os.environ.get("SPACY_NUM_BUILD_JOBS"))
      build_ext_options.build_options(self)
      build_ext.build_extensions(self)
  
file_path: spacy/setup.py
imports: from setuptools import Extension, setup, find_packages
  import sys
  import numpy
  from setuptools.command.build_ext import build_ext
  from sysconfig import get_path
  from pathlib import Path
  import shutil
  from Cython.Build import cythonize
  from Cython.Compiler import Options
  import os
  import subprocess
label_desc: Use image node_id 1 for calling the build_ext_subclass obj's underlying member method code with example usage: obj.build_extensions() without return types