text: def findMid(head):
      if head is None:
          return None
      
      ptr1 = head
      ptr2 = head
      while(ptr2 is not None and ptr2.next is not None):
          ptr1 = ptr1.next
          # this pointer moves 1 nodes ahead everytime loop is run
          
          ptr2 = ptr2.next.next
          # this pointer moves 2 nodes ahead everytime loop is run
      
      return ptr1.data
      # since slow was moving with half speed, it is there at halfway point
  