Description:
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Using a plus or minus sign allows exit to avoid parenthesis. 

The behavior should be consistent : either parenthesis are always needed, either they are optional. 

Either enforce parenthesis in both cases (suggested modification),
or relax parenthesis usage in both cases.

Same applies to die;

Test script:
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exit  1;  <= syntax error
exit (1)  <= executable code
exit -1;  <= executable code
exit +1;  <= executable code

exit -+-1;  <= executable code

exit -$f;  <= executable code
exit $f;  <= syntax error
exit($f);  <= executable code


Expected result:
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exit and die use parenthesis the same way, with or without minus and plus signs.


Actual result:
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exit and die behaves differently parenthesis with or without minus and plus signs.