code: def estimator(request) -> CovarianceEstimator:
      return request.param
  
file_path: arch/arch/tests/covariance/test_covariance.py
imports: from itertools import product
  import numpy
  from numpy.testing import assert_allclose
  import pandas
  import pytest
  from arch.covariance.kernel import Andrews, Bartlett, CovarianceEstimate, CovarianceEstimator, Gallant, NeweyWest, Parzen, ParzenCauchy, ParzenGeometric, ParzenRiesz, QuadraticSpectral, TukeyHamming, TukeyHanning, TukeyParzen
  from arch.typing import ArrayLike
label_desc: Use image node_id 2 for calling a global function with example usage: estimator(request) and returns: request