Yes, it is valid. I am using double braces ("{{" & "}}") to escape "{" and "}" in a format string. Let's assume `maxArgLen` is 10, then the result returned by `Format` method above is
```c#
"  {0, -12}{1}"
```
The result is a format string itself, which is dynamically generated. It is used later to make sure we always have tidy help information.