code: def _has_converged(pi_star, pi):
      
      node_count = pi.shape[0]
      EPS = 10e-6
      for i in range(node_count):
          if pi[i] - pi_star[i] > EPS:
              return False
  
      return True
docs: Checks if the random walk has converged.
  
      :param pi_star: the new vector
      :param pi: the old vector
      :returns: bool-- True iff pi has converged.