Returns a rotated copy of self's digits, value-of-other times.
The second operand must be an integer in the range -precision
through precision. The absolute value of the second operand gives
the number of places to rotate. If the second operand is positive
then rotation is to the left; otherwise rotation is to the right.
The coefficient of the first operand is padded on the left with
zeros to length precision if necessary. The sign and exponent of
the first operand are unchanged.