Method __init__

barcode/isxn.py:103–108

(self, issn, writer=None)

    digits = 7

    def __init__(self, issn, writer=None) -> None:
        issn = issn.replace("-", "")
        issn = issn[: self.digits]
        self.issn = issn
        self.issn = f"{issn}{self._calculate_checksum()}"
        super().__init__(self.make_ean(), writer)

    def _calculate_checksum(self):
        tmp = (