Write the code for the smaller() method in Python 3.7 language and USE RECURSION

class BinarySearchTree: Binary Search Tree class This class represents a binary tree satisfying the Binary Search Tree property: for every node, its value is all items stored in its left subtree, andall items stored in its right subtree. # Private Attributes # The item stored at the root of the tree, or None if the tree is empty. root: Optional [Any] # The left subtree, or None if the tree is empty. left: Optional[BinarySearchTreel # The right subtree, or None if the tree is empty. -right: Optional[BinarySearchTreel def smaller(self, item: Any) ->List: ""Return all of the items in this BST strictly smaller than . As with BinarySearchTree.items, you should *not* need to sort the list yourself! >>bst BinarySearchTree(7) >left - BinarySearchTree(3) >>> left-left = Bina rySearchTree ( 2 ) >>left._rightBinarySearchTree(5) >>> right = Bina rySearchTree (11) >>>right._left -BinarySearchTree(9) >>>right._right-BinarySearchTree(13) bst._left-left >>bst._right -right >>>bst.smaller(6) [2, 3, 5 >>>bst.smaller (13) [2, 3, 5, 7, 9, 11] if self.is_empty) return [] # ADD CODE HERE