/// Another abstraction that this doesn't provide is implementing increment in
/// terms of addition of one. These aren't equivalent for all iterator
/// categories, and respecting that adds a lot of complexity for little gain.
+///
+/// Classes wishing to use `iterator_facade_base` should implement the following
+/// methods:
+///
+/// Forward Iterators:
+/// (All of the following methods)
+/// - DerivedT &operator=(const DerivedT &R);
+/// - bool operator==(const DerivedT &R) const;
+/// - const T &operator*() const;
+/// - T &operator*();
+/// - DerivedT &operator++();
+///
+/// Bidirectional Iterators:
+/// (All methods of forward iterators, plus the following)
+/// - DerivedT &operator--();
+///
+/// Random-access Iterators:
+/// (All methods of bidirectional iterators excluding the following)
+/// - DerivedT &operator++();
+/// - DerivedT &operator--();
+/// (and plus the following)
+/// - bool operator<(const DerivedT &RHS) const;
+/// - DifferenceTypeT operator-(const DerivedT &R) const;
+/// - DerivedT &operator+=(DifferenceTypeT N);
+/// - DerivedT &operator-=(DifferenceTypeT N);
+///
template <typename DerivedT, typename IteratorCategoryT, typename T,
typename DifferenceTypeT = std::ptrdiff_t, typename PointerT = T *,
typename ReferenceT = T &>