gBASIC. `help` for prompt commands, `quit` to leave.
> unknown = ""
false
> unknown = unknown
true
> unknown = nothing
false
> nothing = 0
false
> unknown + 1
runtime error at <prompt>:1:9: unknown cannot be used in arithmetic
> nothing + 1
runtime error at <prompt>:1:9: arithmetic operator '+' expected number but got nothing
> unknown > 5
runtime error at <prompt>:1:9: unknown and nothing support only = and !=
> "You said " + unknown
You said unknown
> default(unknown, "8080")
8080
> quit
