Help for beginner

My program tree sort
i want display tree
(@data (@left, @right))
(@data (@left, @right))
(@data (@left, @right))

My code:
class Tree
attr_accessor :left
attr_accessor :right
attr_accessor :data

def initialize(x=nil)
@left = nil
@right = nil
@data = x
end
def insert(x)
if @data == nil
@data = x
elsif x <= @data
if @left == nil
@left = Tree.new x
else
@left.insert x
end
else
if @right == nil
@right = Tree.new x
else
@right.insert x
end
end
end

def inorder()
@left.inorder {|y| yield y} if @left != nil
yield @data
@right.inorder {|y| yield y} if @right != nil
end

def traverse()
list = []
yield @data
list << @left if @left != nil
list << @right if @right != nil
loop do
break if list.empty?
node = list.shift
yield node.data
list << node.left if node.left != nil
list << node.right if node.right != nil
end
end
end
items = [50, 20, 80, 10, 30, 70, 90, 5, 14,
28, 41, 66, 75, 88, 96]

tree = Tree.new

items.each {|x| tree.insert(x)}

tree.inorder {|x| print x, " "}
print “\n”

Jesus Castello wrote in post #1172357:

What seems to be the problem? Do you get any errors? In the mean time
you may want to check out my implementation here:

ruby-algorithms/binary_search_tree_spec.rb at master · matugm/ruby-algorithms · GitHub

ruby-algorithms/binary_search_tree.rb at master · matugm/ruby-algorithms · GitHub

How I do print ?
(50(20(10(5 nil nil)(14 nil nil))(30(28 nil nil)(41 nil nil)))(80(70(66
nil nil)(75 nil nil))(90(88 nil nil)(96 nil nil))))