Interface OptionalType

interface OptionalType {
    elementType:
        | ArrayType
        | ConditionalType
        | UnknownType
        | IndexedAccessType
        | InferredType
        | IntersectionType
        | IntrinsicType
        | LiteralType
        | MappedType
        | OptionalType
        | PredicateType
        | QueryType
        | ReferenceType
        | ReflectionType
        | RestType
        | TemplateLiteralType
        | TupleType
        | NamedTupleMemberType
        | TypeOperatorType
        | UnionType;
    type: "optional";
}