Nice :) Today it's possible to do a lot of it with vanilla Python (sortof):

   something(lambda x: [
      x2 := x + 10, # define variables

      [ print(f"Number: {i})
        for i in range(x) ], # loop

      [ 0 for i in range(x)
           if print(f"Number: {i}") or True
           if print(f"Second line: {i}") ], # loop if you prefer "normal code order"

      0 if x > 0 else {}[f'{n} should be positive'], # conditions and asserts (throws KeyError, but includes the error message)

      x2 * 2 # return
   ][-1])

note: I'm not responsible for coworkers injuring you after committing this

> in an idiomatic manner

Come on. No. It has the benefit of working, but definitely not being idiomatic.