module to manipulate Structured Tags datastructures

 Data::Stag is for manipulating data as hierarchical tag/value
 pairs (Structured TAGs or Simple Tree AGgreggates). These
 datastructures can be represented as nested arrays, which have the
 advantage of being native to perl. A simple example is shown below:
 .
  [ person=> [ [ family_name => $family_name ],
  [ given_name => $given_name ],
  [ phone_no => $phone_no ] ] ],
 .
 Data::Stag uses a subset of XML for import and export. This
 means the module can also be used as a general XML parser/writer (with
 certain caveats).