I am learning Elixir and wanted to try implementing simple tree traversal algorithms. However, I am not getting the desired results. What am I doing wrong?

defmodule Algos do
    #pre_order function, prints the root, the left then the right
    def pre_order(node, nodes) do
        next = [nodes | node.data]
        if (node && node.left) do
            Algos.pre_order(node.left, next) 
        end
        if (node && node.right) do
            Algos.pre_order(node.right, next)
        end
        next
    end

    #in_order function, prints the left, the root then the right
    def in_order(node, nodes) do
        if (node && node.left) do 
            Algos.in_order(node.left, nodes) 
        end
        next = [nodes | node.data]
        if (node && node.right) do
            Algos.in_order(node.right, next)
        end
        next
    end

    #post_order function, prints the left, the right then the root
    def post_order(node, nodes) do
        if (node && node.left) do
            Algos.post_order(node.left, nodes)
        end
        if (node && node.right) do
            Algos.post_order(node.right, nodes)
        end
        [nodes | node.data]
    end
end

defmodule Traverse do
    def print do
        root = %{
            data: "A",
            left: %{
                data: "B", 
                left: %{
                    data: "C", 
                    left: nil,
                    right: nil
                },
                right: %{
                    data: "D",
                    left: nil, 
                    right: nil
                }
            },
            right: %{
                data: "E", 
                left: nil, 
                right: nil
            }
        }

        result = Algos.pre_order(root, "")
        IO.puts(result)

        result2 = Algos.in_order(root, "")
        IO.puts(result2)

        result3 = Algos.post_order(root, "")
        IO.puts(result3)
    end
end

Traverse.print

The output looks as follows

[Running] elixir "/Volumes/MAC/d/Algorithms/tree_traversal.exs"
A
A
A

[Done] exited with code=0 in 3.891 seconds