Some Control Constructs 

(if 
    if-form
 else-form)

(when 
  then-form-1
  then-form-2
  then-form-n)
  
(unless 
  then-form-1
  then-form-2
  then-form-n)
  
(case 
  ('symbol-matching-var-1 "return-value1")
  ('symbol-matching-var-2 "return-value2")
  ...
  ('symbol-matching-var-n "return-valuen")
  (otherwise "other-return-value"))