Write a function to toggle characters case in a string.
def toggle_string(string):
 string1 = string.swapcase()
 return string1
<s>[INST]<<SYS>>Given a task and its code, generate test cases for the code.<</SYS>>Write a function to toggle characters case in a string.
def toggle_string(string):
 string1 = string.swapcase()
 return string1[/INST]assert toggle_string("Python")==("pYTHON")
assert toggle_string("Pangram")==("pANGRAM")
assert toggle_string("LIttLE")==("liTTle")</s>