swap words

words = 'PythON is CoOL'
new_words = ''
for word in words:
    if str(word).islower():
        new_words+=word.upper()

    elif str(word).isupper():
        new_words+=word.lower()
print(new_words)

def swap_case(s):
    return ''.join(c.lower() if c.isupper() else c.upper() for c in s)