@Nonnull
public String present( @Nonnull StructPart struct ) {
final StringBuilder builder = new StringBuilder();
StructureTreeWalker treeWalker = new DepthFirstStructureTreeWalker();
treeWalker.walk( struct, new StructureTreeWalker.WalkerCallBack() {
@Override
public void nodeReached( @Nonnull StructPart node, int level ) {
for ( int i = 0; i < level; i++ ) {
builder.append( intendSequence );
}