“One Day at a Time” recently escaped a brush with cancellation, so it’s appropriate that the new season begins with a head count to make sure that everyone’s OK.

The occasion is the 2020 census. A government worker (a cameo by Ray Romano) knocks on the apartment door of the Alvarezes, the Cuban-American family that resided for three seasons on Netflix until the streaming service dropped the deeply loved but (we’re told) insufficiently watched sitcom.

The scene serves a practical function for the show, which was saved by the Pop TV network and begins its fourth season Tuesday. For the benefit of a new cable audience, Romano’s character walks us through a thumbnail introduction of everyone: Penelope Alvarez (Justina Machado), a single mother and military veteran; Lydia (Rita Moreno), Penelope’s irrepressible mother; and the Alvarez kids and hangers-on.

As for the longtime fans, you can relax. “One Day at a Time,” in three episodes screened for critics, is fully intact in personnel, laughs and creative mission. The only things missing are a concession to the shorter run times of ad-supported TV: a few minutes off the average episode and, sadly, a sharply truncated version of the addictive theme song. (“This is it,” indeed.)