example string as a Unicode string: Where is … Reykjavík?
example string as a bytes sequence: b'Where is \xe2\x80\xa6 Reykjav\xc3\xadk?'
NFC     True     b'Where is \xe2\x80\xa6 Reykjav\xc3\xadk?'
NFKC    False    b'Where is ... Reykjav\xc3\xadk?'
NFD     False    b'Where is \xe2\x80\xa6 Reykjavi\xcc\x81k?'
NFKD    False    b'Where is ... Reykjavi\xcc\x81k?'