input: Write a python function to count the occurrences of a specific word in a string.
  assert countWord("Python is an interpreted, high-level, general-purpose programming language.", "programming") == 1
  assert countWord("This is a test. This test is only a test.", "test") == 3
  assert countWord("Word word WORD wordy", "word") == 3
output: def countWord(s, word):
      return s.lower().split().count(word.lower())