# isNothing {#isnothing}

## Syntax {#syntax}

`isNothing(X)`

## Arguments {#arguments}

**X** is a scalar/vector.

## Details {#details}

"Nothing" is one of the two objects in VOID type.

`isNothing` tests if a function argument is provided by the user.

## Examples {#examples}

```
f=def(x,y): isNothing(y);
f(5,);
// output: true

f(5, NULL);
// output: false
```

