Parsing a language called "Foo"
                               with the Pegex toolset.    

                              .-----------------------.
  .--------------------.      |    Pegex::Compiler    |
  |    Foo Language    |      |-----------------------|    Serialize
  |--------------------|----->| Pegex::Pegex::Grammar |---------.
  | Pegex grammar text |      | Pegex::Receiver       |         |
  '--------------------'      '-----------------------'         v
  ......................                  |                 .------.
  |                    |                  | compile()       | YAML |
  |foo:: <verb> <noun> |                  v                 '------'
  |verb: /Hello/       |       .--------------------.       .------.
  |noun: /world/       |       | Foo grammar tree   |       | JSON |
  |                    |       '--------------------'       '------'
  ......................                  |                 .------.
                                          |                 | Perl |
                                          v                 '------'
                               .---------------------.      .--------.
                               | Pegex::Foo::Grammar |      | Python |
                               |---------------------|      '--------'
                               | Pegex::Parser       |      .-----.
                               | Pegex::Foo::AST     |      | etc |
   .-----------------.         '---------------------'      '-----'
   |  Foo Language   |                    |
   |-----------------|------------------->| parse()
   | Foo source text |                    v
   '-----------------'        .----------------------.
   ...................        | Parsed Foo Data Tree |
   |Hello world      |        '----------------------'
   ...................        ........................
                              |- verb: Hello         |
                              |- noun: world         |
                              ........................