ftd file, a “library” has to be provided
ftd file can refer to another ftd files using the
feature. So the parsed document contains all data about
ftd files referenced, directly or indirectly from the original file.
The original document’s name must be provided when parsing, in our example,
"some/id", and similarly when getting a variable out parsed state, we have
<doc-id>#<variable-name> format to generate “full id” of any variable.