ExistsOrNonemptyCondition.ceylon
"An existence or nonemptiness condition, that is,
the keyword ‘`exists`’ or ‘`nonempty`’, followed by either an
(optionally typed) specified variable or an (untyped) member name.
Examples:
nonempty employees
exists String name = person.name"
shared abstract class ExistsOrNonemptyCondition()
of ExistsCondition | NonemptyCondition
extends Condition() {
"The variable being tested."
shared formal SpecifiedVariable|LIdentifier variable;
shared actual formal [SpecifiedVariable|LIdentifier] children;
}