I write regex in Expect script and want use **([0-9]+)\r** as regex pattern. To prevent of **[...]** substitution I use curved braces:

```

expect -re {([0-9]+)\r} {...}

```

But **\r** in **{...}** have no special meaning in braces (treated as two chars). I try

```

expect -re {([0-9]+)}\r {...}

```

But this take parsing error. I try

```

expect -re [concat {([0-9]+)} "\r"] {...}

```

But **concat** add space between args.

**PS**. I know another solution with **"..."** quotes by quoting **[**:

```

expect -re "(\[0-9]+)\r" {...}

```

but would like hear solution with **{...}** quoting style...