import codecs, io

try:
    ascii
except NameError:
    ascii = repr

b = b'\x41\xF5\x42\x43\xF4'
print(ascii(b.decode('utf8', 'replace')))
with open('temp.bin', 'wb') as fout:
    fout.write(b)
with codecs.open('temp.bin', encoding='utf8', errors='replace') as fin:
    print(ascii(fin.read()))
with io.open('temp.bin', 'rt', encoding='utf8', errors='replace') as fin:
    print(ascii(fin.read()))