Often, I know that a variable should have one of a set of values, and I want to determine which one, with an if/elif/else clause. This looks something like this: ``` if foo == 1: # do a elif foo == 2: # do b elif foo == 3: # do c else: raise ValueError('foo must be 1, 2 or 3') ``` Sometimes, I just do ``` if foo == 1: # do a elif foo == 2: # do b else: # do c ``` But this is less readable and allows errors to slip past. My proposal is to allow the following syntax: ``` if foo == 1: # do a elif foo == 2: # do b else foo == 3: # do c ``` Or perhaps the more readable version: ``` if foo == 1: # do a elif foo == 2: # do b else assert foo == 3: # do c ``` Both of these options are backward compatible, since currently nothing is allowed between the `else` and the `:`. This would be roughly equivalent to ``` if foo == 1: # do a elif foo == 2: # do b else: assert foo == 3 # do c ``` But shorter and more readable, since it puts the assertion at the same levels as the others. Thoughts?