getDOMImplementation(name = None, features = ()) -> DOM implementation.
Return a suitable DOM implementation. The name is either
well-known, the module name of a DOM implementation, or None. If
it is not None, imports the corresponding module and returns
DOMImplementation object if the import succeeds.
If name is not given, consider the available implementations to
find one with the required feature set. If no implementation can
be found, raise an ImportError. The features list must be a sequence
of (feature, version) pairs which are passed to hasFeature.