/**
  @addtogroup TWG_Storage

  \section sec_TWG_Storage_Concept_Storage Storage Concept
  
  Storage represents a sequence whose elements can be efficiently (constant cost) accessed in random order.
  Storage is related to Sequence Container (<a href="">C++ Standard, Section 23.2.3</a>);
  in fact the following standard containers meet the Storage requirements:
  <ul>
   <li> \c std::vector </li>
   <li> \c std::array </li>
   <li> \c std::valarray </li>
  </ul>

*/