# stdnum.issn

ISSN (International Standard Serial Number).

The ISSN (International Standard Serial Number) is the standard code to identify periodical publications (e.g. magazines).

An ISSN has 8 digits and is formatted in two pairs of 4 digits separated by a hyphen. The last digit is a check digit and may be 0-9 or X (similar to ISBN-10).

More information:

- https://en.wikipedia.org/wiki/International_Standard_Serial_Number
- http://www.issn.org/

    >>> validate('0024-9319')
    '00249319'
    >>> validate('0032147X')
    Traceback (most recent call last):
        ...
    InvalidChecksum: ...
    >>> validate('003214712')
    Traceback (most recent call last):
        ...
    InvalidLength: ...
    >>> compact('0032-1478')
    '00321478'
    >>> format('00249319')
    '0024-9319'
    >>> to_ean('0264-3596')
    '9770264359008'

`stdnum.issn.``calc_check_digit`(number)

  Calculate the ISSN check digit for 10-digit numbers. The number passed should not have the check bit included.

`stdnum.issn.``compact`(number)

  Convert the ISSN to the minimal representation. This strips the number of any valid ISSN separators and removes surrounding whitespace.

`stdnum.issn.``format`(number)

  Reformat the number to the standard presentation format.

`stdnum.issn.``is_valid`(number)

  Check if the number provided is a valid ISSN.

`stdnum.issn.``to_ean`(number, issue_code='00')

  Convert the number to EAN-13 format.

`stdnum.issn.``validate`(number)

  Check if the number is a valid ISSN. This checks the length and whether the check digit is correct.