This is run with uncrustify 0.70.1, and black 19.10b0.
This helps to prevent mistakes, and allows easily changing the ROM value of None if needed.
The aim here is to have spi.c contain the low-level SPI driver which is independent (not fully but close) of MicroPython objects and methods, and the higher-level bindings are separated out to pyb_spi.c and machine_spi.c.
Jim Mussared
Damien George