Caesar changes string to uppercase

[DavidEngNJ]

Hi James
I am using the Caesar cipher to encrypt my text string, which consists of lower and upper case. But, the Caesar method changes it to all upper case. And, when I decrypt it is all upper case, which won't match my original mixed case string. Any suggestions appreciated.

code snippet:
USERNAME = os.environ['NETWORK_USERNAME']
PASSWORD = os.environ['NETWORK_PASSWORD']
from pycipher import Caesar
var1 = Caesar(key=21).encipher(USERNAME,keep_punct=True)
print(var1)
var2 = Caesar(key=21).encipher(PASSWORD,keep_punct=True)
print(var2)