Welcome to Quackery.

Enter "leave" to leave the shell.

/O> $ "" temp put ( move an empty string to temp                                     )
... temp share    ( copy the empty string on temp to the stack                       )
... $ '' =        ( compare the top of stack to an empty string, and replace it with
...                 1 (true) if it is an empty string and 0 (false) if it is not.    )
... temp take     ( move the empty string on temp to the stack                       )
... $ '' !=       ( compare the top of stack to an empty string, and replace it with
...                 1 (true) if it is not an empty string and 0 (false) if it is.    )
...

Stack: 1 0

/O> leave
...

Aloha.