2 nextprime - nearest prime greater than specified number
11 return positive integer or err
14 If n is an integer less than 2^32, nextprime(n) returns the
15 first prime greater than n.
17 If n >= 2^32 or n is fractional, nextprime(n, err) returns the value
20 Other cases cause a runtime error.
23 > print nextprime(10), nextprime(100), nextprime(1e6)
26 > print nextprime(3/2,-99), nextprime(2^32-1,-99), nextprime(2^32,-99)
33 FULL znprime(ZVALUE z)