text: from collections import Counter
  from itertools import chain
  class Solution:
      def uncommonFromSentences(self, A: str, B: str) -> List[str]:
          counter_sen = Counter(chain(A.split(), B.split()))
          uncommon_words = []
          for key, value in counter_sen.items():
              if value == 1:
                  uncommon_words += [key]
          return uncommon_words