Utility that takes as input a credit card number and length of credit card number and returns asterisks and last 4 digits
Usages :
ast.v2 "1234-1234-1234-1234" 16
ast.v2 "1234123412341234" 16
ast.v2 "1234 1234 1234 1234" 16
ast.v2 "1234 1234 1234 1234" 16
ast.v2 "1234-1234-1234-12341" 16
ast.v2 "1234123412341234---" 16
ast.v2 "1919191919191912" 16
ast.v2 "11" 16
ast.v2 "123456789123456789" 16
ast.v2 "123456789123456789123456789123456789123456789123456789" 16
ast.v2 "1234567890123451" 15
ast.v2 "123456789012345" 15
ast.v2 "1234567890" 10