If you use SPI1 or SPI2 and compile for a Teensy 3.2/3.1 it gives a generic error .

error: 'SPI1' was not declared in this scope
SPI1.begin();

If possible it would be nice to say these functions are only usable in T3.5/T3.6 instead of a generic error message that we get. Took me about 2 hours to figure out why it was throwing errors.