comefrom: <qiyuangong>019_Remove_Nth_Node_From_End_of_List_2.py
code: def removeNthFromEnd( head, n):
      if head is None:
          return None
      slow = fast = head
      for i in range(n):
          fast = fast.next
      if fast is None:
          head = head.next
          return head
      while fast.next is not None:
          fast = fast.next
          slow = slow.next
      curr = slow.next
      slow.next = curr.next
      return head
masked: def sample_funcname ( var_0 , var_1 ) :
      if var_0 is None :
          return None
      var_4 = var_3 = var_0
      for var_6 in range ( var_1 ) :
          var_3 = var_3.next
      if var_3 is None :
          var_0 = var_0.next
          return var_0
      while var_3.next is not None :
          var_3 = var_3.next
          var_4 = var_4.next
      var_8 = var_4.next
      var_4.next = var_8.next
      return var_0
  