Create a conjunction of the given predicates.
If the input is empty, return a literal true.
If the input contains a single predicate, return the predicate.
Otherwise, return a conjunction of the predicates (e.g. a AND b AND c).
Create a conjunction of the given predicates.
If the input is empty or the return None.
If the input contains a single predicate, return Some(predicate).
Otherwise, return a Some(..) of a conjunction of the predicates (e.g. Some(a AND b AND c)).