Must be first line in a file:

sub'_{q} tsuJ}}_();sub's{seek+DATA,0,0}sub'p{print&_}sub'r{reverse$_[0
]}@_=(('')x2,split"  ",<DATA>);s!!&s,$_=<DATA>;s/}.*?}/$_[$s+1]/
if$s;s/(}.*?})/r$1/e;eval$_;p,$s++!efor@_[0..3];
__DATA__
} rehtona}  } lreP}  },rekcah}
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