    template <
        class Iterator
      , class Value = use_default
      , class CategoryOrTraversal = use_default
      , class Reference = use_default
      , class Difference = use_default
    >
    class indirect_iterator
    {
     public:
        typedef /* see below */ value_type;
        typedef /* see below */ reference;
        typedef /* see below */ pointer;
        typedef /* see below */ difference_type;
        typedef /* see below */ iterator_category;

        indirect_iterator();
        indirect_iterator(Iterator x);

        template <
            class Iterator2, class Value2, class Category2
          , class Reference2, class Difference2
        >
        indirect_iterator(
            indirect_iterator<
                 Iterator2, Value2, Category2, Reference2, Difference2
            > const& y
          , typename enable_if_convertible<Iterator2, Iterator>::type* = 0 // exposition
        );

        Iterator const& base() const;
        reference operator*() const;
        indirect_iterator& operator++();
        indirect_iterator& operator--();
    private:
       Iterator m_iterator; // exposition
    };

The member types of `indirect_iterator` are defined according to the following pseudo-code, where `V` is `iterator_traits<Iterator>::value_type`

    if (Value is use_default) then
        typedef remove_const<pointee<V>::type>::type value_type;
    else
        typedef remove_const<Value>::type value_type;

    if (Reference is use_default) then
        if (Value is use_default) then
            typedef indirect_reference<V>::type reference;
        else
            typedef Value& reference;
    else
        typedef Reference reference;

    if (Value is use_default) then
        typedef pointee<V>::type* pointer;
    else
        typedef Value* pointer;

    if (Difference is use_default)
        typedef iterator_traits<Iterator>::difference_type difference_type;
    else
        typedef Difference difference_type;

    if (CategoryOrTraversal is use_default)
        typedef iterator-category (
            iterator_traversal<Iterator>::type,``reference``,``value_type``
        ) iterator_category;
    else
        typedef iterator-category (
            CategoryOrTraversal,``reference``,``value_type``
        ) iterator_category;

# `indirect_iterator` requirements

The expression `*v`, where `v` is an object of `iterator_traits<Iterator>::value_type`, shall be valid expression and convertible to `reference`. `Iterator` shall model the traversal concept indicated by `iterator_category`. `Value`, `Reference`, and `Difference` shall be chosen so that `value_type`, `reference`, and `difference_type` meet the requirements indicated by `iterator_category`.

[Note: there are further requirements on the `iterator_traits<Iterator>::value_type` if the `Value` parameter is not `use_default`, as implied by the algorithm for deducing the default for the `value_type` member.]

# `indirect_iterator` models

In addition to the concepts indicated by `iterator_category` and by `iterator_traversal<indirect_iterator>::type`, a specialization of `indirect_iterator` models the following concepts, Where `v` is an object of `iterator_traits<Iterator>::value_type`:

> - Readable Iterator if `reference(*v)` is convertible to `value_type`.
> - Writable Iterator if `reference(*v) = t` is a valid expression (where `t` is an object of type `indirect_iterator::value_type`)
> - Lvalue Iterator if `reference` is a reference type.

`indirect_iterator<X,V1,C1,R1,D1>` is interoperable with `indirect_iterator<Y,V2,C2,R2,D2>` if and only if `X` is interoperable with `Y`.

# `indirect_iterator` operations

In addition to the operations required by the concepts described above, specializations of `indirect_iterator` provide the following operations.

`indirect_iterator();`

Requires: | `Iterator` must be Default Constructible.
Effects: | Constructs an instance of `indirect_iterator` with a default-constructed `m_iterator`.

`indirect_iterator(Iterator x);`

Effects: | Constructs an instance of `indirect_iterator` with `m_iterator` copy constructed from `x`.

    template <
        class Iterator2, class Value2, unsigned Access, class Traversal
      , class Reference2, class Difference2
    >
    indirect_iterator(
        indirect_iterator<
             Iterator2, Value2, Access, Traversal, Reference2, Difference2
        > const& y
      , typename enable_if_convertible<Iterator2, Iterator>::type* = 0 // exposition
    );

Requires: | `Iterator2` is implicitly convertible to `Iterator`.
Effects: | Constructs an instance of `indirect_iterator` whose `m_iterator` subobject is constructed from `y.base()`.

`Iterator const& base() const;`

Returns: | `m_iterator`

`reference operator*() const;`

Returns: | `**m_iterator`

`indirect_iterator& operator++();`

Effects: | `++m_iterator`
Returns: | `*this`

`indirect_iterator& operator--();`

Effects: | `--m_iterator`
Returns: | `*this`