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The book is both a memoir of their experiences in Canada — they were particularly active in the country’s arts community — and a call for a return to its historic relationship with the United States. Mr. Heyman has become one of Canada’s most prominent defenders in the United States since President Trump took office.

Here are some excerpts from a chat we had in Ottawa’s ByWard Market the morning after their book launch this week. It’s been edited for clarity and space:

While you are now back home in Chicago, in some ways you’ve become the ambassador who never left.

BRUCE HEYMAN: When Obama left office we left office effectively. Then as things were developing back home, we started getting phone calls from Canada: Mr. Ambassador, would you mind coming on radio to talk to us and tell us what the heck is going on down there because we’re having a hard time understanding?