code: def _is_valid_correlation_matrix_cholesky_factor(L, tol=1e-6):
      """Check if supplied matrix is a Cholesky factor of a valid correlation matrix
  
      A matrix is a Cholesky fator of a valid correlation matrix if it is lower
      triangular, has positive diagonal, and unit row-sum
  
      Args:
          L: A n x n lower-triangular matrix, or a batch of b lower-triangular
              matrices with shape b x n x n
          tol: The tolerance with which to check positivity of the diagonal and
              unit-sum of the rows
  
      Returns:
          True if L is a Cholesky factor of a valid correlation matrix, False
              otherwise (in batch mode, all matrices in the batch need to be
              Cholesky factors of valid correlation matrices)
  
      """
      unit_row_length = torch.all(
          (torch.norm(L, dim=-1) - 1).abs() < tol
      )
      return unit_row_length and torch.all(
          constraints.lower_cholesky.check(L)
      )
  
imports: import torch
  from linear_operator.utils.cholesky import psd_safe_cholesky
  from torch.distributions import constraints, LKJCholesky
  from torch.nn import Module
  from ..None import settings
  from .prior import Prior
label_desc: Use image node_id 3 for calling a global function with example usage: _is_valid_correlation_matrix_cholesky_factor(L, tol) and returns: unknown