73.dfsTraversal

Write a function named dfsTraversal that receives one parameter as input:

• an object describing the root node of a tree graph. Each node has the following properties:

  • value - the value in this node, which is a number
  • left - the left child of this node - which is an object with the same structure. This property is optional, because not all nodes will have a left child.
  • right - the right child of this node - which is an object with the same structure. This property is optional, because not all nodes will have a right child.

The function should return an Array of numbers corresponding to the values of the tree in DFS (depth-first) order.

NOTE: the left children should be visited before the right ones.