In the name of God;
Testlib has nice random functions, here I want to suggest some other ones. The first and the second random functions are available in testlib, but the rest are not.
1, $$$\text{rnd.next(l, r)}$$$, it will return a random number in range $$$l$$$ to $$$r$$$ with equal probabilities :
2, $$$\text{rnd.wnext(l, r, w)}$$$, it will return a random number in range $$$l$$$ to $$$r$$$ with monotonically increasing/decreasing probabilities :
if $$$w = 0$$$ then it will be equal to $$$\text{rnd.next(l, r)}$$$.
if $$$w > 0$$$ :
if $$$w < 0$$$ :
3, $$$\text{rnd.cnext(l, r, c)}$$$, it will return a random number in range $$$l$$$ to $$$r$$$ :
4, \text{