function ModuloInteger takes integer dividend, integer divisor returns integer
       local integer modulus = dividend - (dividend / divisor) * divisor
       // If the dividend was negative, the above modulus calculation will
       // be negative, but within (-divisor..0).  We can add (divisor) to
       // shift this result into the desired range of (0..divisor).
       if (modulus < 0) then
           set modulus = modulus + divisor
       return modulus

Gets the remainder of dividend divided by divisor as an integer.