code: def unique_justseen(iterable, key=None):
      """Yields elements in order, ignoring serial duplicates
  
      >>> list(unique_justseen('AAAABBBCCDAABBB'))
      ['A', 'B', 'C', 'D', 'A', 'B']
      >>> list(unique_justseen('ABBCcAD', str.lower))
      ['A', 'B', 'C', 'A', 'D']
  
      """
      return map(
          next, map(operator.itemgetter(1), groupby(iterable, key))
      )
  
imports: import warnings
  from collections import deque
  from itertools import chain, combinations, count, cycle, groupby, islice, repeat, starmap, tee, zip_longest
  import operator
  from random import randrange, sample, choice
label_desc: Use image node_id 19 for calling a global function with example usage: unique_justseen(iterable, key) and returns: map