def get_installed_pypackages():
    return {p.project_name.lower(): p for p in pkg_resources.working_set}
def visitdir(self, dir):
        dir = normalizerootdir(dir, "visitdir")
        if self._prefix and dir in self._fileset:
            return "all"
        if not self._prefix:
            return True
        return (
            dir in self._fileset
            or dir in self._dirs
            or any(parentdir in self._fileset for parentdir in util.finddirs(dir))
        )