class_docstr: Filter samples based on text perplexity
  
  Example::
  
      sample 1: "I love textflint", score: 6.7
      sample 2: "I love TextFlinet", score: 6.34
code: def __repr__(self):
      return (
          "LMSubPopulation-"
          + str(self.intervals[0])
          + "-"
          + str(self.intervals[1])
      )
  
file_path: textflint/textflint/generation/subpopulation/UTCN/lm.py
imports: import torch
  import math
  from ..subpopulation import SubPopulation
label_desc: Use image node_id 2 for calling the LMSubPopulation obj's underlying member method code with example usage: obj.__repr__() and returns: unknown