checkdigit.isbn.missing¶

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

Calculates a missing digit in an ISBN Code represented by a question mark.

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

Examples

>>> from checkdigit import isbn
>>> # ISBN-10
>>> isbn.missing("15688?111X")
'1'
>>> # ISBN-13
>>> isbn.missing("978186197876?")
'9'
>>> isbn.missing("023456789128")
'Invalid'