CdmNode.toHash
size_t toHash() const pure nothrow @trustedComputes a hash value for this CdmNode.
This implementation is consistent with opEquals: two nodes that compare equal will have the same hash value. Like opEquals, only the semantic value content is hashed, not metadata (location, format, comments).
Acyclicity precondition: the node graph must be acyclic. Cycles through raw member/attribute pointers are not detected.
Returns
A hash value suitable for use in associative arrays.