code: def maybe_cythonize_extensions(top_path, config):
      
      is_release = os.path.exists(os.path.join(top_path, 'PKG-INFO'))
  
      if is_release:
          build_from_c_and_cpp_files(config.ext_modules)
      else:
          message = ('Please install cython with a version >= {0} in order '
                     'to build a pmdarima development version.').format(
                         CYTHON_MIN_VERSION)
          try:
              import Cython
              if LooseVersion(Cython.__version__) < CYTHON_MIN_VERSION:
                  message += ' Your version of Cython was {0}.'.format(
                      Cython.__version__)
                  raise ValueError(message)
              from Cython.Build import cythonize
          except ImportError as exc:
              exc.args += (message,)
              raise
  
          config.ext_modules = cythonize(config.ext_modules)
docs: Tweaks for building extensions between release and development mode.