I listed the meaning of the abbreviations below, for any one else who might also use the snippet:
LSE = Low-speed external user clock
LSI = Low-speed internal
HSE = High-speed external user clock
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
Sure - there's nothing built-in, but it's what I use for testing:
It checks the actual registers in the chip to see what it's set to.