Even if it's possible to coerce anything to
!! that's absolutely not practical solution. Just imagine counting of
! symbols to understand what we expect
false and then imagine guessing if anything has
+ to numbers also not seems to be practical solution, even if it's somehow expected to work like that. What value it should return, length of containers or inverted negative numbers? The first wouldn't be used so often plus in most of cases it anyway would be used to check for non-zero length, and the second also wouldn't be used so often plus we already have prefix
- which does the same task.