assert((0 second         -> human) == "0 seconds")
assert((1 second         -> human) == "1 second")
assert((5 second         -> human) == "5 seconds")
assert((1.5 second       -> human) == "1.500 seconds")

assert((60 seconds       -> human) == "1 minute")
assert((73 seconds       -> human) == "1 minute + 13 seconds")
assert((120 seconds      -> human) == "2 minutes")
assert((60.1 seconds     -> human) == "1 minute + 0.100 seconds")
assert((1 minute         -> human) == "1 minute")
assert((1.25 minute      -> human) == "1 minute + 15 seconds")
assert((2.5 minute       -> human) == "2 minutes + 30 seconds")

assert((1 hour           -> human) == "1 hour")
assert((1.5 hour         -> human) == "1 hour + 30 minutes")
assert((2 hour           -> human) == "2 hours")
assert((1 hour + 1 sec   -> human) == "1 hour + 1 second")

assert((1 day            -> human) == "1 day")
assert((1.37 day         -> human) == "1 day + 8 hours + 52 minutes + 48 seconds")

assert((1 week           -> human) == "7 days")
assert((1.5 weeks        -> human) == "10 days + 12 hours")
assert((2 weeks          -> human) == "14 days")

assert((1 sidereal_day   -> human) == "23 hours + 56 minutes + 4.090500 seconds")

assert((10000 days       -> human) == "10000 days")
assert((50 million days  -> human) == "50_000_000 days")

assert((1e12 days        -> human) == "1_000_000_000_000 days")
assert((1e15 days        -> human) == "1.0e+15 days")

assert((1 ms             -> human) == "0.001 seconds")
assert((1 µs             -> human) == "0.000001 seconds")
assert((1 ns             -> human) == "0.000000001 seconds")
assert((1234 ns          -> human) == "0.000001234 seconds")
assert((1s + 1234 ns     -> human) == "1.000001234 seconds")