Implement a function that counts the number of nodes in a circularly linked list

# Python3 program to count number of nodes in
# a circular linked list.
 
# structure for a node
class Node:
    def __init__(self, data):
        self.data = data
        self.next = None
 
# Function to insert a node at the beginning
# of a Circular linked list */
def push(head_ref,data):
 
    ptr1 = Node(0)
    temp = head_ref
    ptr1.data = data
    ptr1.next = head_ref
 
    # If the linked list is not None then set
    # the next of last node
    if (head_ref != None) :
        while (temp.next != head_ref):
            temp = temp.next
        temp.next = ptr1
    else:
        ptr1.next = ptr1 #For the first node */
 
    head_ref = ptr1
    return head_ref
 
# Function to print nodes
# in a given Circular linked list
def countNodes(head):
 
    temp = head
    result = 0
    if (head != None) :
        while True :
            temp = temp.next
            result = result + 1
            if (temp == head):
                break
     
    return result
 
# Driver Code
if __name__=='__main__':
 
    # Initialize lists as empty */
    head = None
    head = push(head, 12)
    head = push(head, 56)
    head = push(head, 2)
    head = push(head, 11)
 
    print( countNodes(head))
     
# This code is contributed by Arnab Kundu