首字母大写并增加标点关卡（Correct Sentence）：
def correct_sentence(text: str) -> str:
"""
returns a corrected sentence which starts with a capital letter
and ends with a dot.
"""
your code here
text=text[0].upper()+text[1:]
if text[-1]!='.':
text=text+"."
return text
return textif name == 'main':
print("Example:")
print(correct_sentence("greetings, friends"))
# These "asserts" are used for self-checking and not for an auto-testing
assert correct_sentence("greetings, friends") == "Greetings, friends."
assert correct_sentence("Greetings, friends") == "Greetings, friends."
assert correct_sentence("Greetings, friends.") == "Greetings, friends."
assert correct_sentence("hi") == "Hi."
print("Coding complete? Click 'Check' to earn cool rewards!")