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<?php $a0 = 'ab' $a1 = 'a'; $a2 = 'b'; print ${$a1 + $a2};
Output for 5.4.2 - 5.4.45, 5.5.24 - 5.5.30, 5.6.7 - 5.6.14
Parse error: syntax error, unexpected '$a1' (T_VARIABLE) in /in/N70lb on line 4
Process exited with code 255.

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