test-fixtures/aleph-sequential/valuelessSubfield
{
"leader": "12345cam a22002417i 4500",
"fields": [
{"tag": "001", "value": "000123456"},
{"tag": "003", "value": "(FI-MELINDA)"},
{"tag": "005", "value": "20210730133112.0"},
{"tag": "500", "ind1": " ", "ind2": " ", "subfields": [{"code": "a"}]}
]
}