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values = [True, False, True, None, True]
print(['yes' if v is True else 'no' if v is False else 'unknown' for v in values])
# ['yes', 'no', 'yes', 'unknown', 'yes']
# Above is equivalent to:
result = []
for v in values:
if v is True:
result.append('yes')
else:
if v is False:
result.append('no')
else:
result.append('unknown')
print(result)
# ['yes', 'no', 'yes', 'unknown', 'yes']