code: def logdet_sinv_np(X, sigma):
      # logdet
      sign, logdet = np.linalg.slogdet(sigma)
      logdet_np = sign * logdet
      # sigma-inv
      sinv_np = np.linalg.inv(sigma)
      # solve
      sinvx_np = np.linalg.solve(sigma, X)
      return logdet_np, sinv_np, sinvx_np
  
imports: import pytest
  import numpy
  from numpy.testing import assert_allclose
  from scipy.stats import norm, wishart, invgamma, invwishart
  import tensorflow
  from brainiak.matnormal.covs import CovIdentity, CovAR1, CovIsotropic, CovDiagonal, CovDiagonalGammaPrior, CovUnconstrainedCholesky, CovUnconstrainedCholeskyWishartReg, CovUnconstrainedInvCholesky, CovKroneckerFactored
label_desc: Use image node_id 1 for calling a global function with example usage: logdet_sinv_np(X, sigma) and returns: logdet_np,  sinv_np,  sinvx_np