recursive descend parser - avoiding left recursion
===

I have the following productions
      
    A -> Aa
    A -> b
so it is clear that there is left recursion like

    parseA() {
       parseA();//recursion
       parsea();
    }

It is said that the left recursion can be avoided using the following rule
 

    A -> bA'
    A' -> aA'|null


How is left recursion avoided here?.There is still recursion in function A'.
Can anybody explain me this.I am a beginner in this subject?