Method: ((SETF LOOKUP-TAL-VARIABLE) T T LIST)

Source

(defmethod (setf lookup-tal-variable) (value name (env list))
  (loop
     for bind-set in env
     do (multiple-value-bind (old-value found-p)
            (fetch-tal-value name bind-set)
	  (declare (ignore old-value))
          (when found-p
	    (return-from lookup-tal-variable
	      (setf (fetch-tal-value name bind-set) value)))))
  (error 'unfound-tal-variable :variable-name name :environment env))