Algorithm will detect any single-digit error, as well as almost all transpositions of adjacent digits. It will not, however, detect transposition of the two-digit sequence 09 to 90 (or vice versa).
It is not intended to be a cryptographically secure hash function. It is mostly used for pre-flight credit card number validation as specified in ISO/IEC 7812-1:2015
import luhn
ok = luhn.Validate("00123014764700968325")
digit = luhn.Digit("x")
signed = luhn.Generate("1")