code: List<MathNode> filterSameChildren(MathNode searchNode, List<MathNode> list) {
          return list.stream().filter(searchNode::equals).collect(Collectors.toList());
      }
docs: Filter for similar nodes from a list. Only the node itself will be compared.
  We will not look at their respective children.
  <br/>
  This method is used when we want to compare children from different nodes
  out of order.
  
  @param searchNode node we want to find.
  @param list       list we want to search.
  @return new list with the same node we search for.