code: def read_str(self):
      length = self.read_u64()
      data = self.f.read(length)
      return data.decode()
  
imports: import struct
  import functools
  import torch
  import numpy
  from io import BufferedReader
  from tqdm import tqdm
  from bigdl.llm.utils.common import invalidInputError
label_desc: Use image node_id 14 for calling the GGUFReader obj's underlying member method code with example usage: obj.read_str() and returns: data