initions of the corresponding concepts.
For each concept we define a concept checking class template where the
template parameter is for the type to be checked.  The class contains
a <tt>contraints()</tt> member function which exercises all of the
valid expressions of the concept. The objects used in the constraints
function, such as <tt>n</tt> and <tt>i</tt>, are declared as data
members of the concept checking class.

<pre>
  template &lt;class Iter&gt;
  struct RandomAccessIterator_concept
  {
    void c