code: def get_chain(seed=1234, ndim=3, N=100000):
      np.random.seed(seed)
      a = 0.9
      x = np.empty((N, ndim))
      x[0] = np.zeros(ndim)
      for i in range(1, N):
          x[i] = x[i - 1] * a + np.random.rand(ndim)
      return x
  
file_path: emcee/src/emcee/tests/unit/test_autocorr.py
imports: import numpy
  import pytest
  from emcee.autocorr import AutocorrError, integrated_time
label_desc: Use image node_id 1 for calling a global function with example usage: get_chain(seed, ndim, N) and returns: x