So glad that departing President Barack Obama took the time to pen a “Dear Don” letter for incoming President Trump.

POTUS 44 went full professor in his do as I say, not as I did admonishments.

“It’s up to us to do everything we can (to) build more ladders of success for every child and family that’s willing to work hard,” reads Obama’s first commandment. An astounding statement from a president who did his best to pile all of the “ladders of success” and burn them in a regulatory bonfire. Under-employment under Obama was historic and Obamacare pummeled small businesses mercilessly.

“American leadership in this world really is indispensable. It’s up to us, through action and example, to sustain the international order that’s expanded steadily since the end of the Cold War, and upon which our own wealth and safety depend.”

No, seriously. He wrote that.

It is possible no other president in American history did more to stoke chaos and disorder in the world and less to “sustain order” than Barack “Red Line” Obama, who kicked off his presidency with the infamous apology tour. He abandoned Iraq, facilitating the rise of ISIS. He wrecked Libya and cowered in Syria — letting Russia step in. He backed down on missile defense for Eastern Europe and stood by as an emboldened Vladimir Putin invaded Crimea. He put Iran on the nuclear fast track, and impotently watched as North Korea honed its nuclear missile technology.

“We are just temporary occupants of this office. That makes us guardians of those democratic institutions and traditions — like rule of law, separation of powers, equal protection and civil liberties — that our forebears fought and bled for. Regardless of the push and pull of daily politics, it’s up to us to leave those instruments of our democracy at least as strong as we found them.”

Obama’s IRS persecuted conservative groups. He used intelligence agencies to investigate the media. There is increasing evidence that his Justice Department — at his guidance — snuffed an investigation into Hillary Clinton. And it now appears his administration actively spied on the Trump campaign, unmasking monitored conversations involving Trump associates.

“Take time, in the rush of events and responsibilities, for friends and family.”

Tell that to Aunt Zeituni, who lived in public housing in South Boston, while her nephew lived in the White House.

Thanks, Barack. If only you had taken your own advice.