str.islower
Check that all letters of the string are lowercase.
Python 3.13
str.islower()Return value
True or False; False for a string without letters.
Examples
Lowercase letters only
Python 3.13
print('hello'.islower())True
One uppercase letter
Python 3.13
print('python 3'.islower(), 'Python'.islower())True False
Details
Characters without case, such as digits, spaces and punctuation, do not affect the check, but there must be at least one letter: "2024".islower() gives False.