I know you’ve said it: It’s good to expect the best but prepare for the worst.

So it is with this ongoing investigation being led by the Justice Department’s special counsel, Robert Mueller III. He appears to be wrapping up his lengthy probe into Donald Trump’s conduct as a presidential candidate and as president of the United States.

Mueller’s probe has focused on allegations of collusion between the Trump campaign and Russian operatives who attacked our electoral system. It’s also examining possible conspiracy and obstruction of justice matters, too. There might be a violation or two of the Constitution’s Emoluments Clause, which prohibits presidents from accepting gifts from foreign kings, potentates and assorted heads of state.

The media are now reporting that the FBI has looked into whether the president acted as a foreign agent for Russia, our nation’s pre-eminent hostile power. This is frightening stuff.

I won’t call it the “best” outcome, but a better outcome would be if Mueller has uncovered the truth into what many of us have suspected all along, that Trump is inherently corrupt. I suspect Mueller will produce a thorough finding of fact and will deliver it to Congress’s doorstep for full public review, absent the redacted material that deals with national security matters.

The worst outcome will be that he has nothing, that Trump has been right all along, that there is “no collusion.” Why is that the worst? Because none of us is going to hear the end of it from the president. He will be in our faces for as long as he holds office and likely beyond that time. He will launch a torrent of Twitter messages that expound on the “witch hunt” allegation he has been leveling at Mueller.

To be candid, it appears that the likelihood that Mueller comes up empty is diminishing. It looks for all the world that he has something, although what precisely it is remains known only to Mueller and his team of legal eagles.

However, if he does reveal that he has nothing, well . . . we all should be ready. Those of us who are critical of the president have praised Mueller’s professionalism in his pursuit of the truth. If that pursuit produces nothing, then we are dutybound to accept those findings.

I don’t believe that will happen. But if it does . . .