code: def test_thin_by(backend, progress):
      with backend() as be:
          with pytest.raises(ValueError):
              run_sampler(be, thin_by=-1)
          with pytest.raises(ValueError):
              run_sampler(be, thin_by=0.1)
          nsteps = 25
          thinby = 3
          sampler1 = run_sampler(
              None, nsteps=nsteps * thinby, progress=progress
          )
          sampler2 = run_sampler(
              be, thin_by=thinby, progress=progress, nsteps=nsteps
          )
          for k in ["get_chain", "get_log_prob"]:
              a = getattr(sampler1, k)()[thinby - 1 :: thinby]
              b = getattr(sampler2, k)()
              c = getattr(sampler1, k)(thin=thinby)
              assert np.allclose(a, b), "inconsistent {0}".format(k)
              assert np.allclose(a, c), "inconsistent {0}".format(k)
          assert sampler1.iteration == sampler2.iteration * thinby
  
imports: import pickle
  from itertools import islice, product
  import numpy
  import pytest
  from emcee import EnsembleSampler, backends, moves, walkers_independent
label_desc: Use image node_id 6 for calling a global function with example usage: test_thin_by(backend, progress) without return types