input: Write a python function to count the frequencies of words in a string.
  assert countFrequencies("This is a test string") == {"This": 1, "is": 1, "a": 1, "test": 1, "string": 1}
  assert countFrequencies("hello world hello") == {"hello": 2, "world": 1}
  assert countFrequencies("one one two three three three") == {"one": 2, "two": 1, "three": 3}
output: def countFrequencies(s):
      words = s.split()
      frequency = {}
      for word in words:
          if word in frequency:
              frequency[word] += 1
          else:
              frequency[word] = 1
      return frequency