code: public static <T> TypeChecker<Collection<? extends T>> tCollection(TypeChecker<? extends T> elementChecker) {
          return new CollectionTypeChecker<>(Collection.class, elementChecker);
      }
docs: Creates a recursing type checker for a {@link java.util.Collection}.
  
  @param elementChecker The typechecker to check the elements with
  @return a typechecker for a Collection containing elements passing the specified type checker