# Readable Iterator Concept

A class or built-in type `X` models the Readable Iterator concept for value type `T` if, in addition to `X` being Assignable and Copy Constructible, the following expressions are valid and respect the stated semantics. `U` is the type of any specified member of type `T`.

Readable Iterator Requirements (in addition to Assignable and Copy Constructible)
Expression | Return Type | Note/Precondition
--- | --- | ---
`iterator_traits<X>::value_type` | `T` | Any non-reference, non-cv-qualified type
`*a` | Convertible to `T` |

pre: `a` is dereferenceable. If `a == b` then `*a`
  is equivalent to `*b`.

`a->m` | `U&` | pre: `pre: (*a).m` is well-defined. Equivalent to `(*a).m`.