- These classes contain the documentations of the concepts. In order

 - These classes contain the documentations of the concepts. In order

   to avoid document multiplications, an implementation of a concept

   to avoid document multiplications, an implementation of a concept

   simply refers to the corresponding concept class.

   simply refers to the corresponding concept class.

   implementation of the concepts should provide, however completely

   implementation of the concepts should provide, however completely

   without implementations and real data structures behind the

   without implementations and real data structures behind the

   interface. On the other hand they should provide nothing else. All

   interface. On the other hand they should provide nothing else. All

   the algorithms working on a data structure meeting a certain concept

   the algorithms working on a data structure meeting a certain concept

   should compile with these classes. (Though it will not run properly,

   should compile with these classes. (Though it will not run properly,

   of course.) In this way it is easily to check if an algorithm

   of course.) In this way it is easily to check if an algorithm

   doesn't use any extra feature of a certain implementation.

   doesn't use any extra feature of a certain implementation.

   that makes it possible check whether a certain implementation of a

   that makes it possible check whether a certain implementation of a

   concept indeed provides all the required features.

   concept indeed provides all the required features.

 - Finally, They can serve as a skeleton of a new implementation of a concept.

 - Finally, They can serve as a skeleton of a new implementation of a concept.