# Boolean Logic

## `not`
```
(not value)
```
`not` returns nil if `value` is non-nil, otherwise, it returns `t`.

## `or`
```
(or &rest values)
```

`or` returns its first non-nil argument, or nil if all arguments are
nil.

## `and`
```
(and &rest values)
```
`and` returns its last argument if all arguments are non-nil, or nil if
it encounters a nil argument.