code: def pair_dict_key_sets(pair_dict):
      row_keys = set([])
      column_keys = set([])
      for row_key, column_key in pair_dict.keys():
          row_keys.add(row_key)
          column_keys.add(column_key)
      return row_keys, column_keys
  
imports: from collections import defaultdict
  import numpy
  from scipy.sparse import dok_matrix
label_desc: Use image node_id 13 for calling a global function with example usage: pair_dict_key_sets(pair_dict) and returns: row_keys,  column_keys