class_docstr: Replacer class for replacing HLO instructions by FileCheck captures.
code: def _replacer(self, m: re.Match) -> str:
      instr_name = m.group(0)
      if instr_name in self._replacement_cache:
          return self._replacement_cache[instr_name]
      replacement_instr = self._generate_unique_varname(instr_name)
      self._replacement_cache[instr_name] = f"[[{replacement_instr}]]"
      return "".join([f"[[{replacement_instr}:", r"%[^ ]+", "]]"])
  
file_path: tensorflow-upstream/third_party/xla/xla/service/generate_test_hlo_checks.py
imports: import re
  import shutil
  import sys
  import tempfile
  from typing import Dict
label_desc: Use image node_id 3 for calling the FileCheckVarReplacer obj's underlying member method code with example usage: obj._replacer(m) and returns: str, self