appendCopy method
Appends a deep copy of node (which may live in another stream info's
description) as the last child; returns the copy.
Implementation
LSLXmlNode appendCopy(LSLXml node) {
final copyPtr = lsl_append_copy(xmlPtr, node.xmlPtr);
if (copyPtr.isNullPointer) {
throw LSLException('Failed to append copy of node');
}
return LSLXmlNode.fromXmlPtr(copyPtr);
}