?!
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?! is an esolang, invented by User:None1. It has only 2 commands, but it is still Turing complete.
Commands
Just like its name, ?! has only 2 commands, which are ? (question mark) and ! (exclamation mark).
Because it has only these two commands you can interleave it with brainfuck or oOo CODE.
Execution
! command
Every ! command is interpreted as one of the command in brainfuck, which is called the "current command", the current command is initially +.
? command
Switch current command to the command right after the current command in +-,.<>[], each time the ? command is executed, It changes how ?! interprets !. If the current command is ], It becomes +.
Note that in ?!, when the brainfuck ] command is executed, it changes back to [ if the condition to jump is satisfied.
Example Programs
Cat Program
!??????!????!?!????!
Explaination
! Execute + ?????? Switch command to [ ! Execute [ ???? Switch command to , ! Execute , ? Switch command to . ! Execute . ???? Switch command to ] ! Execute ]
Hello World
!!!!!!!!??????!???????!???!!!!??????!???????!???!!?????!???!!!?????!???!!!?????!???!????!!!!?????!??????!??????!???!?????!???! ?????!????!????!!???!??????!??????!???!?????!?????!??????!??????!!??????!??!????!!!??!?????!!!!!!!???!!?????!!!???!??!!??????! ?!?????!??!?!???????!?????!!!???!??????!!!!!!??!??????!!!!!!!!??!??!!???!???!??!???!!???!