code: def _apply_replace_backrefs(m, repl=None, flags=0):
      
  
      if m is None:
          raise ValueError("Match is None!")
      else:
          if isinstance(repl, ReplaceTemplate):
              return repl.expand(m)
          elif isinstance(repl, (str, bytes)):
              return _bregex_parse._ReplaceParser().parse(m.re, repl, bool(flags & FORMAT)).expand(m)
docs: Expand with either the `ReplaceTemplate` or compile on the fly, or return None.