XQuery XML Universal Quantifier Help

Hi,

I'm not sure if this is the right section to ask but,

I need help with using universal quantifier in XQuery.
I have a set of strings like ("yes", "no, "yes", "no") and I need it to check if every element is "yes"

I have:

if (every $answer in $list satisfies ($answer='yes'))
then ...
else ()

But it is a lexing error.

I have also tried

$answer eq yes
$answer="yes"
without brackets etc..

What should be the correct syntax?

Thanks.