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* Added method to turn off the LED entirely.
* Fixed method errors for `Device.set_led`.
* Fixed bug preventing orange LED from being set (was not using the
orange-specific brightness of `0x04`, a constraint not present for other
colors; but makes perfect sense given voltage, etc).
* Fixed bug preventing LED being set to full brightness in some cases by using
`0x0f` instead of `0x10` for `MAX_BRIGHTNESS`.
* Give the device a quarter-second to report back after sending LED state
commands, so the buffer doesn't get polluted with the response next time we
try to open the device (though the long-term fix here is a read until we
start getting measurement records, if I'm not mistaken)