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())
            )

        Iterate over the search path to locate and load fullname.
        
product/runtime/src/main/python/pkg_resources/extern/__init__.py