&key reader writer accessor => new-value
Arguments and Values:
new-value — A value to set the property to.
object — An object.
property-name — A symbol which names the property to set.
reader — A symbol, T, or NIL
writer — A symbol, T, or NIL
accessor — A symbol, T, or NIL
Description:
(SETF PROPERTY-VALUE)will set new-value as one of object's direct properties. If property-name names an existing direct property, the value is changed. If property-name is not already a direct property of object, the new value is set locally, and will shadow any values for that property that have been set in object's precedence list.