Today's lab will explore using both method_missing and blocks.

Download tree.rb from the course website.  Add an each_node method
that takes a block and applies it to every node in the tree.  For
this to work correctly, you will most likely need to explicitly name
the block.

Once you have that working, use method_missing to add support for
fetching the value on a given path through arbitrary method name.
Some examples:

my_tree.left_left

my_tree.left_left_right

my_tree.right_left_right

my_tree.left_right_left_left_right_left_left_right_left_left_right


The scan method from the String class may be useful.