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<lang PicoLisp>(unless MyNewVariable
(handle value-is-NIL) )</lang>
=={{header|Pike}}==
In Pike all variables are initialized to <math>0</math>, regardless of their type. thus <math>0</math> functions as a <code>Null</code> value for all types except integer.
<math>0</math> is also used to indicate the absence of a key or object member.
to tell the difference between a value <math>0</math> and absence of a key, <code>zero_type()</code> is used:
<lang Pike>> mapping bar;
> bar;
Result: 0
> bar = ([ "foo":0 ]);
> bar->foo;
Result 0;
> zero_type(bar->foo);
Result: 0
> bar->baz;
Result: 0
> zero_type(bar->baz);
Result: 1</lang>
=={{header|PL/I}}==
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