#
# Yes, but that isn't what is wanted by the user in question.
# It's a case of boolean-valued environment variables, to indicate
# certain products are installed. Most people don't bother to define
# such an environment variable on their system, to indicate they haven't
# installed the product, so false() is the natural default in this case.
It would be much better to meet that requirement through an extension
function xx:is-installed('product-name').
Michael Kay
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