Module hints 

Remedies for the failures people actually hit when opening a device.

The same wording backs both the --help troubleshooting section and the error message printed when opening the device fails, so the two can’t drift.

Constants

BUSY_HINT

Another process holds the USB interface.

PERMISSION_HINT

The OS refused access to the USB device node.

Functions

indent

Indent every non-empty line, for embedding a hint in the --help sections.

open_failure_hint

Pick the remedy for a device-open failure, if there is a specific one.