This module inherits from XML::Tidy which in turn inherits from XML::XPath.
This ensures that Merge objects' indenting can be tidied up after any merge
operation since such modification usually spells the ruination of indentation.
Polymorphism allows Merge objects to be utilized as normal XML::XPath objects
The merging behavior is setup to combine separate XML documents according to
certain rules and configurable options. If both documents have root nodes which
are elements of the same name, the documents are merged directly. Otherwise,
one is merged as a child of the other. An optional XPath location can be
specified as the place to perform the merge. If no location is specified, the
merge is attempted at the first matching element or is appended as the new last
child of the other root if no match is found.