Knowing when it doesn't know

Three words say how careful to be. They are not thresholds — you never name a number.

from gut import likely
 
likely(email, "the customer threatens to cancel", lean="yes")
likely(email, "the customer threatens to cancel", ask_human=True)
likely(email, "the customer threatens to cancel", stakes="high", lean="yes", ask_human=True)

• lean — "yes", "no", or nothing. Which mistake is worse, so which way to err.
• ask_human — whether UNSURE is possible at all. Off by default; nothing becomes three-valued behind your back.
• stakes — "low", "medium", "high". How bad an automatic mistake is next to a person looking instead. Only widens the range where a person is asked, so it needs ask_human=True; gut warns if you pass it without.

The two knobs are independent on purpose: being more careful must never quietly change which way you err. lean fixes where yes overtakes no; stakes only widens the band around it.

Below the range it answers no, above it answers yes, inside it asks. Print the table yourself, so you never have to take this page's word for it:

import gut
 
for preset in gut.presets():
    print(preset)

classify and rate take stakes and ask_human too, where they become a confidence floor. They do not take lean: there is no safer side of a four-way choice.

if and match

if decision: works. YES is truthy, NO is falsy, and UNSURE is an explicit choice rather than a silent one:

import gut
 
gut.configure(on_unsure="raise")   # default: raises UnsureDecision
gut.configure(on_unsure="false")   # or "true", or a callback
 
with gut.on_unsure("false"):       # scoped; follows async tasks, never leaks across threads
    ...

The default raises because coercing UNSURE to False is the most dangerous option available: it is what your existing if already does, so the third branch would vanish down the "no" path — the exact bug this library exists to prevent, reintroduced as a default.

In a match, the outcomes must be dotted. A bare case YES: is not a value pattern in Python, it is a capture pattern that matches anything, and the compiler rejects it:

SyntaxError: name capture 'YES' makes remaining patterns unreachable

import gut
from gut import Outcome
 
match decision:
    case gut.YES: ...
    case gut.NO: ...
 
match decision:
    case Outcome.YES: ...