Load latest check point.

    Parameters
    ----------
    with_local: bool, optional
        whether the checkpoint contains local model

    Returns
    -------
    tuple : tuple
        if with_local: return (version, gobal_model, local_model)
        else return (version, gobal_model)
        if returned version == 0, this means no model has been CheckPointed
        and global_model, local_model returned will be None

def load_checkpoint(with_local=False):
    """Load latest check point.

    Parameters
    ----------
    with_local: bool, optional
        whether the checkpoint contains local model

    Returns
    -------
    tuple : tuple
        if with_local: return (version, gobal_model, local_model)
        else return (version, gobal_model)
        if returned version == 0, this means no model has been CheckPointed
        and global_model, local_model returned will be None
    """
    gptr = ctypes.POINTER(ctypes.c_char)()
    global_len = ctypes.c_ulong()
    if with_local:
        lptr = ctypes.POINTER(ctypes.c_char)()
        local_len = ctypes.c_ulong()
        version = _LIB.RabitLoadCheckPoint(
            ctypes.byref(gptr),
            ctypes.byref(global_len),
            ctypes.byref(lptr),
            ctypes.byref(local_len))
        if version == 0:
            return (version, None, None)
        return (version,
                _load_model(gptr, global_len.value),
                _load_model(lptr, local_len.value))
    else:
        version = _LIB.RabitLoadCheckPoint(
            ctypes.byref(gptr),
            ctypes.byref(global_len),
            None, None)
        if version == 0:
            return (version, None)
        return (version,
                _load_model(gptr, global_len.value))