This probably warrants some more explanation. The truth is that all the parser needs is `\{`, but currently the way you format this into a string literal is via the syntax `\\{` because you must first, in the rust source file, excape the `\` character, and then in the format string you use the `\` to escape the `{`.

Also below, I think that `\\\\{` is a syntax error because `\\\\` becomes `\` and then the `{` is expected to be the start of a format string.