code: public static boolean isRootNode(LeftTupleNode node, TerminalNode removingTN) {
          return node.getType() == NodeTypeEnums.LeftInputAdapterNode || isNonTerminalTipNode( node.getLeftTupleSource(), removingTN );
      }
docs: Returns whether the node is the root of a segment.
  Lians are always the root of a segment.
  
  node cannot be null.
  
  The result should discount any removingRule. That means it gives you the result as
  if the rule had already been removed from the network.