randi(n: number): number

rand() but floored to integer.
randi(10) // returns 0 to 9

randi(a: number, b: number): number

rand() but floored to integer.
randi(0, 3) // returns 0, 1, or 2

randi(): number

rand() but floored to integer.
randi() // returns either 0 or 1