code: def ref_log_det(x):
      # calculate determinant
      y = np.zeros(x.shape[0], dtype=np.float32)
      for i in range(x.shape[0]):
          y[i] = np.linalg.det(x[i])
      # apply abs log
      y = np.abs(y)
      y = np.log(y)
      return y
  
imports: import pytest
  import numpy
  import nnabla
  import nnabla.functions
  from nbla_test_utils import list_context
label_desc: Use image node_id 1 for calling a global function with example usage: ref_log_det(x) and returns: y