# bytes.append

## Function

Append data and return new Bytes.

## Syntax

```bt
bytes(value).append(data)
```

## Parameters

| Parameters | Type | Required | Default value | Description |
|------|------|------|------|------|
| data | String/Array/Bytes | Yes | None | The data to append. String is encoded in UTF-8; Array elements must be 0 to 255; Bytes appends raw bytes directly. |

## Return value

| Type | Description |
|------|------|
| Bytes | New Bytes after appending. |

## Code Example

```bt
data = bytes('B').append('T')

// Output: 4254
print data.to_hex()
```

## Notes

- `append()` does not modify the original Bytes.
- The total length after appending is still limited by `BT_BYTES_LIMIT`.