Sorted order insertion of linked list in python 3

Python program for Sorted order insertion of linked list. Here problem description and explanation.

#    Python 3 program for
#    Add node in sorted order of linked list

#  Linked list node
class LinkNode :
	def __init__(self, data) :
		self.data = data
		self.next = None
	

class SingleLL :
	def __init__(self) :
		self.head = None
	
	#  Add new node in sorted order
	def sortedAdd(self, data) :
		#  Create new node
		node = LinkNode(data)
		if (self.head == None or self.head.data >= data) :
			#  When linked list empty
			#  or new nodes are adding at beginning
			node.next = self.head
			self.head = node
		else :
			temp = self.head
			#  Find position to add new node
			while (temp.next != None and 
                   temp.next.data < data) :
				#  Visit to next node
				temp = temp.next
			
			node.next = temp.next
			#  Add new node
			temp.next = node
		
	
	#  Display linked list element
	def display(self) :
		if (self.head == None) :
			return
		
		temp = self.head
		#  Iterating linked list elements
		while (temp != None) :
			print(temp.data , end = " → ")
			#  Visit to next node
			temp = temp.next
		
		print(" NULL")
	

def main() :
	sll = SingleLL()
	#  Add Linked list node
	sll.sortedAdd(1)
	sll.sortedAdd(-3)
	sll.sortedAdd(9)
	sll.sortedAdd(4)
	sll.sortedAdd(11)
	sll.sortedAdd(-7)
	print(" Linked List ")
	#  -7 → -3 → 1 → 4 → 9 → 11 → NULL
	sll.display()

if __name__ == "__main__": main()

Output

 Linked List
-7 → -3 → 1 → 4 → 9 → 11 →  NULL