Inspired by How about to simplify the factorial function name? - #14 by jar1.

Say I want to define `!(x) = factorial(x)`

. I can do that in a module

```
julia> baremodule M
import Base
!(x) = Base.factorial(x)
Base.@show !5
end
!5 = 120
```

but I can’t do it in the repl:

```
julia> !(x) = factorial(x)
ERROR: error in method definition: function Base.! must be explicitly imported to be extended
```

I don’t want to extend `Base.!`

, so the advice it gives is not relevant. Is it possible to define `!`

in the repl? Can I have a `bare`

repl?