Sequences

1. Introduction
2. A simple example
3. Concepts
   1. Sequence
   2. ForwardSequence
   3. BidirectionalSequence
   4. RandomAccessSequence
4. Classes
   1. list
   2. vector?
   3. list_c?
   4. range?
5. Algorithms
   1. size?
   2. empty?
   3. front?
   4. back?
   5. at?
   6. push_front?
   7. push_back?
   8. insert