# Level 1

``!0``

# Level 2

``str_rot13``

# Level 3

``1.``

# Level 4

``0``

# Level 5

``𐍈``

# Level 6

``($x=session_id)($x).$x``

# Level 7

``(object)[!0]``

# Level 8

``new class extends Bar{}``

# Level 9

``A``

# Level 10

``function(&$a){$a=new$a(1);}``

# Level 11

``[]``