uassert expr [descr]

This function is useful for verifying that a condition holds.

If expr denotes a false value in Tcl style, then the assertion fails. In this case, the driver shuts down in panic mode.

If descr is supplied, then it is part of the diagnostic message logged by the system when the driver shuts down.

For example:

...
uassert [expr $int_seq == $extn_seq] {Out of sync}
...