As you all know we can use defun to define a function in the common lisp,
(defun add (x) (+ x 1)) (defun foo (a b c) (list a b c)) Definition above is the most essential method to create a function. Due to the
convience we will have to think about the variables and functions again.
Writing thinking path: from thinking the variables to functions and get the knowledge of the common lisp.