Lingua::Treebank::HeadFinder - Head-finding in Lingua::Treebank

  use Lingua::Treebank;

  my @utterances = Lingua::Treebank->from_penn_file($filename);

  foreach (@utterances) {
    # $_ is a Lingua::Treebank::Const now

    foreach ($_->get_all_terminals) {
      # $_ is a Lingua::Treebank::Const that is a terminal (word)

      print $_->word(), ' ' $_->tag(), "\n";
    }

    print "\n\n";

  }

  Lingua::Treebank::HeadFinder is an object that reads a
  Magerman-style head-finding list and performs headfinding on
  Lingua::Treebank::Const trees.

  The L::TB::HeadFinder object is initialized from a list like the one in 

To do