import re
documents = ["sent1. sent2. sent3. sent4. sent5.", "sent 1. sent 2... sent 3.... sent 4. sent 5..", "sent1.sent2.sent3.sent4.sent5."]
dot_space_regex = re.compile(r'(?<=\.)\s+')
for doc in documents:
	print(dot_space_regex.split(doc))