To prepare gs1-128 feature, refactors the check digit computation. Also, does some cleanings: - Removes unusused check_ean method; - Converts comments into docstrings; - Makes needed changes to avoid linter errors (PEP 8). task-1968113 Co-authored-by: ryv-odoo<ryv@odoo.com>
In anticipation of refactoring, adds some tests to be sure all still keep working as it should do. task-1968113 Co-authored-by: ryv-odoo<ryv@odoo.com>
According to the docstring, the given ean is a string but was summed. Closes #16813