Returns name of MPS device that will be used, else None.

def mps_device_name():
    """
    Returns name of MPS device that will be used, else None.
    """
    lib = _load_tcmps_lib()
    if lib is None:
        return None

    n = 256
    c_name = (_ctypes.c_char * n)()
    ret = lib.TCMPSMetalDeviceName(_ctypes.byref(c_name), _ctypes.c_int32(n))
    if ret == 0:
        return _decode_bytes_to_native_string(c_name.value)
    else:
        return None