[procedure] pairwise-not=? compare x1 ...

SRFI-67: Tests if the values x1 ...(zero or more values) are pairwise unequal with respect to the compare procedure compare. The result is a boolean (either #t or #f). The order in which the values are compared is unspecified, but each value is compared at least once (even if there is just one).

The values x1, ..., x[n] are pairwise unequal if (not=? compare x[i] x[j]) for all i /= j.