isLikelyColumnarV2Header function
Returns whether data is long enough to carry the sketch header and
starts with the v2 magic (little-endian).
Implementation
bool isLikelyColumnarV2Header(Uint8List data) {
if (data.length < 4) return false;
final u32 = ByteData.sublistView(data, 0, 4).getUint32(0, Endian.little);
return u32 == columnarV2Magic;
}