class_docstr: Tversky index
  
  https://en.wikipedia.org/wiki/Tversky_index
  https://github.com/Yomguithereal/talisman/blob/master/src/metrics/tversky.js
class_docstr_tok: ["Tversky","index","https",":","\/\/en.wikipedia.org\/wiki\/Tversky_index","https",":","\/\/github.com\/Yomguithereal\/talisman\/blob\/master\/src\/metrics\/tversky.js"]
code: def __init__(
      self,
      qval: int = 1,
      ks: Sequence[float] = None,
      bias: float | None = None,
      as_set: bool = False,
      external: bool = True,
  ) -> None:
      self.qval = qval
      self.ks = ks or repeat(1)
      self.bias = bias
      self.as_set = as_set
      self.external = external
  
imports: from __future__ import annotations
  from functools import reduce
  from itertools import islice, permutations, repeat
  from math import log
  from typing import Sequence
  from .base import Base, BaseSimilarity
  from .edit_based import DamerauLevenshtein
label_desc: Use image node_id 1 to create a new Tversky object from inherited base classes: _BaseSimilarity with example: obj = Tversky(qval, ks, bias, as_set, external)