How to write attributes in many lines?

[kamil-cy]

Hi,

I'm trying to use Hypertag with Htmx (htmx.org) and I've bump into a problem with validation like here (https://htmx.org/docs/#validation):

<form hx-post="/test">
  <input _="on htmx:validation:validate
               if my.value != 'foo'
                  call me.setCustomValidity('Please enter the value foo')
               else
                  call me.setCustomValidity('')"
         name="example">
</form>

I've tried to use backslash:

form hx-post="/test"
    input _= "on htmx:validation:validate \
               if my.value != 'foo' \
                  call me.setCustomValidity('Please enter the value foo') \
               else \
                  call me.setCustomValidity('')" name="example"

but it gives me an error SyntaxErrorEx: invalid syntax near line 2: input _= "on ht...
It has to be multi-line, so raw string is not an option. Any suggestions appreciated.

Thanks for any help and great job on Hypertag.