if (base case 1)
  // return some simple expression
else if (base case 2)
  // return some simple expression
else if (base case 3)
  // return some simple expression
else if (recursive case 1) {
  // some work before 
  // recursive call 
  // some work after 
 }
else if (recursive case 2) {
  // some work before 
  // recursive call 
  // some work after 
 }
else { // recursive case 3 
  // some work before 
  // recursive call 
  // some work after 
 }