input: Write a python function to detect a loop in a linked list.
  assert detect_loop(Node(1)) == False
  node1 = Node(1)
  node2 = Node(2)
  node3 = Node(3)
  node1.next = node2
  node2.next = node3
  node3.next = node1
  assert detect_loop(node1) == True
  node4 = Node(4)
  node4.next = node1
  assert detect_loop(node4) == True
output: class Node:
      def __init__(self, value):
          self.value = value
          self.next = None
  
  def detect_loop(head):
      slow_ptr = head
      fast_ptr = head
  
      while slow_ptr and fast_ptr and fast_ptr.next:
          slow_ptr = slow_ptr.next
          fast_ptr = fast_ptr.next.next
          
          if slow_ptr == fast_ptr:
              return True
  
      return False