input: Write a function to find the word that appears most frequently in a provided list of strings.
  assert most_frequent_word(["UTS is best for RTF", "RTF love UTS", "UTS is best"] ) == 'UTS'
  assert most_frequent_word(["Its been a great year", "this year is so worse", "this year is okay"] ) == 'year'
  assert most_frequent_word(["Families can be reunited", "people can be reunited", "Tasks can be achieved "] ) == 'can'
output: def most_frequent_word(strings):
      word_count = {}
      for sentence in strings:
          words = sentence.split()
          for word in words:
              word_count[word] = word_count.get(word, 0) + 1
      max_count = max(word_count.values())
      for word, count in word_count.items():
          if count == max_count:
              return word