Because **SETF** is a macro, it can examine the form of the place it’s assigning to and expand into appropriate lower-level operations to manipulate that place. When the place is a variable, it expands into a call to the special operator **SETQ**, which, as a special operator, has access to both lexical and dynamic bindings.15 For instance, to assign the value 10 to the variable x, you can write this:

(setf x 10)

will have no effect on any value outside of . The binding that was created when foo was called is set to 10, immediately replacing whatever value was passed as an argument. In particular, a form such as the following:

  (foo y)

**SETF** can also assign to multiple places in sequence. For instance, instead of the following:

(setf x 1 y 2)

**SETF** returns the newly assigned value, so you can also nest calls to **SETF** as in the following expression, which assigns both and y the same random value: