As with the Document class,
instances have a .node attribute
that points to the contained DOM Element node.
# - - - - - c l a s s E l e m e n t - - - - -
class Element:
"""Represents one XML element.
State/Invariants:
.node: [ a DOM Element node containing the actual element ]
.doc:
[ the Document element rooting the tree containing
the parent ]
"""