func (tc *treeCodec) deepcopy(src *treeCodec) {
	tc.probTree.deepcopy(&src.probTree)
}
deepcopy initializes tc as a deep copy of the source.
package lzma
type treeCodec struct {
	probTree
}
func makeTreeCodec(bits int) treeCodec {
	return treeCodec{makeProbTree(bits)}
}