def METHOD_NAME(self, module_str: str):
    """Load an IPython extension by its module name.
    Returns the string "already loaded" if the extension is already loaded,
    "no load function" if the module doesn't have a load_ipython_extension
    function, or None if it succeeded.
    """
    try:
        return self._load_extension(module_str)
    except ModuleNotFoundError:
        if module_str in BUILTINS_EXTS:
            BUILTINS_EXTS[module_str] = True
            return self._load_extension("IPython.extensions." + module_str)
        raise