'I don't understand this tree structure

type Item = string
type tree = LEAF of Item
          | NODE of tree list

I'm having trouble understanding this. For example:

Node [Node [Item "a", Item "h", Item "b"], Item "k", Node [Item "c", Item "h", Item "d"]]

Could you draw a graph of this? It would be a great help.

It's not that I don't know about trees.

tree

Solution 1:^[1]

The tree that is described by that syntax, corresponds to this visualisation:

      Node
     /  |  \
  Node  k  Node
  / | \    / | \
 a  h  b  c  h  d

The structure is such that only leaves (i.e. Item) have data (of type string). Internal nodes (Node) do not have data.

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Solution	Source
Solution 1	trincot