code: def test_blob_mismatch(backend):
      with backend() as be:
          np.random.seed(42)
  
          model = VariableLogProb()
          coords = np.random.randn(32, 3)
          nwalkers, ndim = coords.shape
  
          sampler = EnsembleSampler(nwalkers, ndim, model, backend=be)
  
          model.i += 1
          # We don't save blobs from the initial points
          # so blob shapes are taken from the first round of moves
          sampler.run_mcmc(coords, 1)
  
          model.i += 1
          with pytest.raises(ValueError):
              sampler.run_mcmc(coords, 1)
  
file_path: emcee/src/emcee/tests/unit/test_blobs.py
imports: import warnings
  import numpy
  import pytest
  from emcee import EnsembleSampler, backends
label_desc: Use image node_id 2 for calling a global function with example usage: test_blob_mismatch(backend) without return types