code: def is_upper_triangular(matrix):
      """True if matrix is 0 on diagonal and below."""
      for src in range(np.shape(matrix)[0]):
          for dst in range(0, src + 1):
              if matrix[src, dst] != 0:
                  return False
  
      return True
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import copy
  import random
  import time
  import shelve
  import hashlib
  import _pickle
  import numpy
label_desc: Use image node_id 1 for calling a global function with example usage: is_upper_triangular(matrix) and returns: True, False