input: Write a python function to calculate the number of sentences that can be classified as boredom in a given string. A sentence is considered boredom if it begins with the word 'I'. Sentences within the string are divided by '.', '?' or '!'.
  assert count_boredom_sentences("Hello world") == 0
  assert count_boredom_sentences("Is the sky blue?") == 0
  assert count_boredom_sentences("I love It !") == 1
  assert count_boredom_sentences("bIt") == 0
  assert count_boredom_sentences("I feel good today. I will be productive. will kill It") == 2
  assert count_boredom_sentences("You and I are going for a walk") == 0
output: def count_boredom_sentences(text):
      sentences = text.split('. ')
      boredom_count = 0
      for sentence in sentences:
          for sub_sentence in sentence.split('? '):
              for part in sub_sentence.split('! '):
                  if part.strip().startswith('I'):
                      boredom_count += 1
      return boredom_count