input: Write a function to split text into sentences based on punctuation marks like '.', '!', and '?'.
  assert split_sentences('This is a test string with three sentences!') == ['This is a test string with three sentences!']
  assert split_sentences('Hello! How are you doing? I am doing fine.') == ['Hello!', ' How are you doing?', ' I am doing fine.']
  assert split_sentences('No punctuation here') == []
output: def split_sentences(text):
      import re
      sentences = re.split(r'(?<=[.!?]) +', text)
      return [s for s in sentences if re.search(r'[.!?]', s)]