Member predicate BuiltInOperationIsUnion :: getAPrimaryQlClass
Gets the name of a primary CodeQL class to which this element belongs.
For most elements, this is simply the most precise syntactic category to
which they belong; for example,
AddExpr is a primary class, but
BinaryOperation is not.
This predicate can have multiple results if multiple primary classes match. For some elements, this predicate may not have a result.