How to use the clldutils.dsv.UnicodeWriter function in clldutils

return v.value
        if isinstance(col.type, JSONEncodedDict):
            return json.dumps(v)
        if isinstance(v, (datetime, date)):
            return v.isoformat()
        return v

    keys = [col.name for col in table.columns]
    cols = {col.name: col for col in table.columns}
    rows = [keys]

    for row in DBSession.execute(select([table])):
        rows.append([conv(row[key], cols[key]) for key in keys])

    if len(rows) > 1:
        with UnicodeWriter(fpath) as writer:
            writer.writerows(rows)

{
                "columnReference": "DomainElement",
                "reference": {
                    "resource": fname.name,
                    "columnReference": "ID"
                }
            }
        ]
        header = ['ID', 'Name', 'Numeric', 'Description']
        ds.metadata['tables'].append({
            'url': fname.name,
            'tableSchema': {
                'columns': [{'name': n, 'datatype': 'string'} for n in header]
            }
        })
        with UnicodeWriter(fname) as writer:
            writer.writerow(header)
            for de in sorted(domain, key=lambda d: (d.parameter_pk, d.number)):
                writer.writerow([de.id, de.name, de.number, de.description])

    ds.write(outdir)