The `rand`

built-in function has the form:

fun rand = (uint<32> seed = 0) int<32>:

It returns a pseudo-random number in the range of the unsigned 32-bit
integers. If a `seed` different to zero is provided, it is used
to initialize a new sequence of pseudo-random numbers (which includes
the one returned.)

The `gettime`

builtin function can be used in order to seed the
pseudo-random number generator very easily:

srand (gettime[1])