Returns true if the argument is a non-empty sequence.
fn:exists( $arg as item()*xs:booleanIf the value of $arg is a non-empty sequence, the function returns
true; otherwise, the function returns false.
The expression fn:exists(fn:remove(("hello"), 1)) returns false().
The expression fn:exists(fn:remove(("hello", "world"), 1)) returns true().
The expression fn:exists([]) returns true().
The expression fn:exists(map{}) returns true().
The expression fn:exists("") returns true().
Assuming $in is an element with no children:
The result is true().