text: import importlib.util
  import sys
  
  
  class VendorImporter:
      """
      A PEP 302 meta path importer for finding optionally-vendored
      or otherwise naturally-installed packages from root_name.
      """
  
      def __init__(self, root_name, vendored_names=(), vendor_pkg=None):
          self.root_name = root_name
          self.vendored_names = set(vendored_names)
          self.vendor_pkg = vendor_pkg or root_name.replace('extern', '_vendor')
  
      @property
      def search_path(self):
          """
          Search first the vendor package then as a natural package.
          """
          yield self.vendor_pkg + '.'
          yield ''
  
      def _module_matches_namespace(self, fullname):
          """Figure out if the target module is vendored."""
          root, base, target = fullname.partition(self.root_name + '.')
          return not root and any(map(target.startswith, self.vendored_names))
  
      def load_module(self, fullname):
          """
          Iterate over the search path to locate and load fullname.
          """
          root, base, target = fullname.partition(self.root_name + '.')
          for prefix in self.search_path:
              try:
                  extant = prefix + target
                  __import__(extant)
                  mod = sys.modules[extant]
                  sys.modules[fullname] = mod
                  return mod
              except ImportError:
                  pass
          else:
              raise ImportError(
                  "The '{target}' package is required; "
                  "normally this is bundled with this package so if you get "
                  "this warning, consult the packager of your "
                  "distribution.".format(**locals())
              )
  
      def create_module(self, spec):
          return self.load_module(spec.name)
  
      def exec_module(self, module):
          pass
  
      def find_spec(self, fullname, path=None, target=None):
          """Return a module spec for vendored names."""
          return (
              importlib.util.spec_from_loader(fullname, self)
              if self._module_matches_namespace(fullname) else None
          )
  
      def install(self):
          """
          Install this importer into sys.meta_path if not already present.
          """
          if self not in sys.meta_path:
              sys.meta_path.append(self)
  
  
  names = 'packaging', 'pyparsing', 'ordered_set',
  VendorImporter(__name__, names, 'setuptools._vendor').install()
  