input: Write a Python function that calculates the number of "boredom" instances in a given string of sentences. A "boredom" is any sentence that starts with the word 'I'. Sentences are separated by '.', '?' or '!'.
  assert count_boredom_occurrences("Hello world") == 0
  assert count_boredom_occurrences("Is the sky blue?") == 0
  assert count_boredom_occurrences("I love It !") == 1
  assert count_boredom_occurrences("bIt") == 0
  assert count_boredom_occurrences("I feel good today. I will be productive. will kill It") == 2
  assert count_boredom_occurrences("You and I are going for a walk") == 0
output: def count_boredom_occurrences(s):
      sentences = s.split('. ')
      count = 0
      for sentence in sentences:
          if sentence.startswith('I'):
              count += 1
      return count