Becouse every time when there is string concatenation a new variable is created in separate pice of mamory. Tis how python work, this solution is simple to implement but it use a lot more memory then solutions without string concatenation.

It gets the job done, but using enumarate() is more pythonic.

Good practice is to add spaces between concatenation.

Dont thik its look like "Best practice", first becouse of string concatenation, second is redundant for loop.