code: def ls_ppl(model, tokenizer, inputs):
      print("=========lightseq=========")
      print("lightseq calculating ppl...")
      ls_ppl, ls_time = ls_gpt2(model, inputs, "ppl")
      print(f"lightseq time: {ls_time}s")
      print("lightseq results:")
      print(ls_ppl)
  
imports: import time
  import torch
  from torch import nn
  from transformers import GPT2Tokenizer, GPT2LMHeadModel, GPT2Config
  import lightseq.inference
  from lightseq.training.ops.pytorch.quantization import qat_mode, QuantLinear, TensorQuantizer, weight_quant_config, emb_quant_config
  from lightseq.training.ops.pytorch.torch_transformer_layers import TransformerDecoderLayer
  from export.util import parse_args
label_desc: Use image node_id 6 for calling a global function with example usage: ls_ppl(model, tokenizer, inputs) without return types