format

    pub fn format(ctx: FormatId, writer: *Writer) Writer.Error!void {
        const bytes = ctx.bytes;
        if (isValidId(bytes) and
            (ctx.flags.allow_primitive or !isPrimitive(bytes)) and
            (ctx.flags.allow_underscore or !isUnderscore(bytes)))
        {
            return writer.writeAll(bytes);
        }
        try writer.writeAll("@\"");
        try stringEscape(bytes, writer);
        try writer.writeByte('"');
    }