checkdigit.luhn.missing¶

checkdigit.luhn.missing(data: str) → str[source]¶

Calculates a missing digit in a luhn code.

Parameters:: data – A string of characters representing a full luhn code with a question mark for a missing character
Returns:: The missing value that should’ve been where the question mark was
Return type:: str

Examples

>>> from checkdigit import luhn
>>> luhn.missing("54175611658527?")
'7'
>>> luhn.missing("515853022?76176")
'1'
>>> luhn.missing("78369216316")
'Invalid'