input: Write a function to find the word that appears most frequently in the provided list of strings.
  assert most_occurrences(["UTS is best for RTF", "RTF love UTS", "UTS is best"] ) == 'UTS'
  assert most_occurrences(["Its been a great year", "this year is so worse", "this year is okay"] ) == 'year'
  assert most_occurrences(["Families can be reunited", "people can be reunited", "Tasks can be achieved "] ) == 'can'
output: def most_occurrences(str_list):
      from collections import Counter
      words = []
      for s in str_list:
          words.extend(s.split())
      return Counter(words).most_common(1)[0][0]