input: Write a python function to count the occurrences of each word in a given string.
  assert word_count("Python is an interpreted high-level programming language") == {'Python': 1, 'is': 1, 'an': 1, 'interpreted': 1, 'high-level': 1, 'programming': 1, 'language': 1}
  assert word_count("test test test word word") == {'test': 3, 'word': 2}
  assert word_count("one two two three three three") == {'one': 1, 'two': 2, 'three': 3}
output: def word_count(s):
      words = s.split()
      word_dict = {}
      for word in words:
          if word in word_dict:
              word_dict[word] += 1
          else:
              word_dict[word] = 1
      return word_dict