# XO0153: unknown or malformed escape sequence

Escapes in `Str` and `Bytes` are `\n \t \r \0 \\ \" \' \$ \xHH \u{...}`. Anything else after a backslash is an error, as are `\x` without two hex digits, `\u` without braces, an invalid code point, and in `Str` a `\xHH` above `\x7f` (use `\u{...}` for non ASCII text). To write a backslash, double it, or use a raw string `r"..."`, which has no escapes. See core 1.6.

## Example

```xo
fn f() -> Str {
  "\q"
}
```

## Fix

```xo
fn f() -> Str {
  r"\q"
}
```

Run `xo explain XO0153` for this text in a terminal, or see
[section 10.6 of the specification](../../spec/core/#106-diagnostic-codes).