Create a function that returns the smallest number of changes it takes to transform one number into one with identical digits. A step is incrementing or decrementing a digit by one.
smallest_transform(399) ➞ 6
# 399 transformed to 999 in 6 steps.
smallest_transform(1234) ➞ 4
# 1234 can be transformed to either 2222 or 3333 using 4 steps.
smallest_transform(153) ➞ 4
smallest_transform(33338) ➞ 5
smallest_transform(7777) ➞ 0
If a number already has identical digits, return 0.