Break internal references within the DOM so that it will be garbage
collected on versions of Python without cyclic GC. Even when cyclic
GC is available, using this can make large amounts of memory available
sooner, so calling this on DOM objects as soon as they are no longer
needed is good practice. This only needs to be called on the
Document object, but may be called on child nodes to discard
children of that node.
Write XML to the writer object. The writer should have a
write() method which matches that of the file object
Return the XML that the DOM represents as a string.
The following standard DOM methods have special considerations with