class List( int value; List next; );
	
void printList( List source; ) {
	print( "{ " );
	while ( source != null ) {
		print( source.value );
		source = source.next;
		if ( source != null )
			print( ", " );
		}
	println( " }" );
	}
	
void createNode( int level; var List dest; int value; List next; ) {
	dest = new List{ value, next };
	 // Show state at this point
	}
	
void insertList( int level; List source; var List dest; int value; ) {
	if ( source == null || value <= source.value ) {
		createNode( level + 1, dest, value, source );
			// Inside the above invocation
		}
	else {
		createNode( level + 1, dest, source.value, null ); 
		insertList( level + 1, source.next, dest.next, value );
			// Inside the above invocation
		}
	}
	
List source, a2, a4, a7, a9, dest;
a9 = new List{ 9, null };
a7 = new List{ 7, a9 };
a4 = new List{ 4, a7 };
a2 = new List{ 2, a4 };
source = a2;
insertList( 0, source, dest, 5 );	// Inside this invocation
printList( source );
printList( dest );