Remove tops from beer cans with can opener; lightly oil insides. Sprinkle soda on dates. Heat beer to boiling and pour over date/soda mixture; set aside to cool. cream together butter, maple syrup, vanilla, and eggs. Stir in flour. Add nuts and cooled date mixture. Spoon batter into cans, filling only ½ full. Bake with cans standing up on cookie sheet, at 350 °F for 15–30 minutes; look for tops to split and test for doneness. Do not cut bread for 1 day; bread may break up, if it is sliced while still warm.