docstr: Construct a pair of MVNs.
docstr_tok: ["Construct","a","pair","of","MVNs","."]
code: def _mvn_pair(self, loc, cov_operator):
      """Construct a pair of MVNs."""
      tril = mvn_tril.MultivariateNormalTriL(
          loc=loc, scale_tril=cov_operator.cholesky().to_dense()
      )
      low_rank_update = (
          MultivariateNormalLowRankUpdateLinearOperatorCovariance(
              loc=loc, cov_operator=cov_operator, validate_args=True
          )
      )
      return MVNPair(low_rank_update=low_rank_update, tril=tril)
  
imports: import collections
  from absl.testing import parameterized
  import numpy
  import tensorflow.compat.v1
  import tensorflow.compat.v2
  from tensorflow_probability.python.distributions import mvn_low_rank_update_linear_operator_covariance
  from tensorflow_probability.python.distributions import mvn_tril
  from tensorflow_probability.python.internal import test_util
  from tensorflow_probability.python.stats import sample_stats
label_desc: Use image node_id 3 for calling the MultivariateNormalLowRankUpdateLinearOperatorCovarianceTest obj's underlying member method code with example usage: obj._mvn_pair(loc, cov_operator) and returns: MVNPair