Stephen Sondheim's score for Assassins has always impressed me for how the late composer-lyricist captured the flavors of Americana: Sousa-like marches, barber shop quartet, folk ballad, and soft pop music, in telling a story that is inherently American. Quibble if you must about the musical's themes, but there is no other musical more relevant in the post-Trump era than Assassins. Some have called it anti-…