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# set(+Tree0, ++Key, ?Value, -Tree)

Update the value corresponding to a key in a tree, inserting the key if it doesn't exist already.

Tree0
  A 2-3-4 tree
Key
  A key to set
Value
  The value corresponding to Key
Tree
  The tree after setting

## Description

If the key Key already exists in the tree Tree0, then this predicate updates the corresponding value to be Value. Otherwise it inserts the key Key into the tree with value Value. The resulting tree is Tree.

This predicate should only be called with trees created by other predicates from the tree234 module.

### Fail Conditions

Never fails.

### Resatisfiable

no

## See Also

insert / 4, update / 4