code: def lower_triangular_matrix(diagonal, non_diagonal):
      return LowerTriangularMatrix()(diagonal, non_diagonal)
  
imports: from functools import lru_cache
  from chainer import cuda
  from chainer import function
  from chainer.utils import type_check
  import numpy
label_desc: Use image node_id 15 for calling a global function with example usage: lower_triangular_matrix(diagonal, non_diagonal) and returns: LowerTriangularMatrix