How to pass curly brace inside sightly expression?

Hi, I have snippet like this:

<sly data-sly-use.svg="${'/apps/foobar/svg.js' @ pngPath={{iconPath}}, iconSize='xs', title={{label}}, desc='', alt={{label}}}">

                                ${svg.html @ context= 'unsafe'}

                            </sly>

I'd like to pass the handlebars expression using double curly braces '{{ foo }}' to the sightly variable, but I got error

token recognition error at: '{'

I think it because sightly process curly brace and not bypass it. How can I pass that curly brace?

Thank you.