comefrom: <qiyuangong>142_Linked_List_Cycle_II_1.py
code: def detectCycle( head):
      try:
          fast = head.next.next
          slow = head.next
      
          while fast != slow:
              fast = fast.next.next
              slow = slow.next
      except:
          return None
      slow = head
      while fast != slow:
          fast = fast.next
          slow = slow.next
      return fast
masked: def sample_funcname ( var_0 ) :
      try :
          var_2 = var_0.next.next
          var_3 = var_0.next
          while var_2 != var_3 :
              var_2 = var_2.next.next
              var_3 = var_3.next
      except :
          return None
      var_3 = var_0
      while var_2 != var_3 :
          var_2 = var_2.next
          var_3 = var_3.next
      return var_2
  