class_docstr: longest common substring similarity
      
class_docstr_tok: ["longest","common","substring","similarity"]
code: def _custom(self, *sequences: str) -> str:
      short = min(sequences, key=len)
      length = len(short)
      for n in range(length, 0, -1):
          for subseq in find_ngrams(short, n):
              joined = "".join(subseq)
              for seq in sequences:
                  if joined not in seq:
                      break
              else:
                  return joined
      return type(short)()
  
imports: from __future__ import annotations
  from difflib import SequenceMatcher
  from typing import Any
  from ..utils import find_ngrams
  from .base import BaseSimilarity
  from .types import TestFunc
label_desc: Use image node_id 2 for calling the LCSStr obj's underlying member method code with example usage: obj._custom() and returns: type, joined