How to use the d3-dsv.dsv function in d3-dsv

function auto(x) {
    var delimiter = autoDelimiter(x);
    if (!delimiter) return null;
    return deleteColumns(dsv.dsv(delimiter).parse(x));
}

delimiters.forEach(function(delimiter) {
        var res = dsv.dsv(delimiter).parse(x);
        if (res.length >= 1) {
            var count = keyCount(res[0]);
            for (var i = 0; i < res.length; i++) {
                if (keyCount(res[i]) !== count) return;
            }
            results.push({
                delimiter: delimiter,
                arity: Object.keys(res[0]).length,
            });
        }
    });

function dsv(data, format) {
  if (data) {
    var h = format.header;
    data = (h ? h.join(format.delimiter) + '\n' : '') + data;
  }
  return d3_dsv.dsv(format.delimiter).parse(data);
}

featurecollection = { type: 'FeatureCollection', features: features };

    if (crs !== '') {
        featurecollection.crs = { type: 'name', properties: { name: crs } };
    }

    if (options.delimiter === 'auto' && typeof x == 'string') {
        options.delimiter = autoDelimiter(x);
        if (!options.delimiter) return callback({
            type: 'Error',
            message: 'Could not autodetect delimiter'
        });
    }

    var parsed = (typeof x == 'string') ?
        dsv.dsv(options.delimiter).parse(x) : x;

    if (!parsed.length) return callback(null, featurecollection);

    var errors = [];

    var noGeometry = false;

    if (!latfield || !lonfield) {
        for (var f in parsed[0]) {
            if (!latfield && isLat(f)) latfield = f;
            if (!lonfield && isLon(f)) lonfield = f;
        }
        if (!latfield || !lonfield) {
            noGeometry = true;
        }
    }